diff --git a/apps/apps.h b/apps/apps.h
index 4a3e1a88573eed9c55baf99ca621b640631cd201..34c3fd8633c1e8dbd948cf5f736e43a4cfeffc0b 100644
--- a/apps/apps.h
+++ b/apps/apps.h
@@ -7,8 +7,8 @@
  * https://www.openssl.org/source/license.html
  */
 
-#ifndef HEADER_APPS_H
-# define HEADER_APPS_H
+#ifndef OSSL_APPS_H
+# define OSSL_APPS_H
 
 # include "e_os.h" /* struct timeval for DTLS */
 # include "internal/nelem.h"
diff --git a/apps/timeouts.h b/apps/timeouts.h
index e023b0aa49209ac6ed36a9cc821cfa701d082b46..7e606cba0b20ac2bf02eafc60a9b31f2084ebfe8 100644
--- a/apps/timeouts.h
+++ b/apps/timeouts.h
@@ -7,11 +7,11 @@
  * https://www.openssl.org/source/license.html
  */
 
-#ifndef INCLUDED_TIMEOUTS_H
-# define INCLUDED_TIMEOUTS_H
+#ifndef OSSL_APPS_TIMEOUTS_H
+# define OSSL_APPS_TIMEOUTS_H
 
 /* numbers in us */
 # define DGRAM_RCV_TIMEOUT         250000
 # define DGRAM_SND_TIMEOUT         250000
 
-#endif                          /* ! INCLUDED_TIMEOUTS_H */
+#endif                          /* ! OSSL_APPS_TIMEOUTS_H */
diff --git a/apps/vms_term_sock.h b/apps/vms_term_sock.h
index c4d1702d799ecc7d7c0a8138a21df10519aaa36a..e092b18eaa7d80c70cf1d79ef947e19e3a5c1b83 100644
--- a/apps/vms_term_sock.h
+++ b/apps/vms_term_sock.h
@@ -8,8 +8,8 @@
  * https://www.openssl.org/source/license.html
  */
 
-#ifndef TERM_SOCK_H
-# define TERM_SOCK_H
+#ifndef OSSL_APPS_VMS_TERM_SOCK_H
+# define OSSL_APPS_VMS_TERM_SOCK_H
 
 /*
 ** Terminal Socket Function Codes
diff --git a/crypto/aes/aes_local.h b/crypto/aes/aes_local.h
index adee29df8d91a248f253dfc38396713d82ea4b1b..cc8456861d928e684e07abea7f7ef6fa98b3b103 100644
--- a/crypto/aes/aes_local.h
+++ b/crypto/aes/aes_local.h
@@ -7,8 +7,8 @@
  * https://www.openssl.org/source/license.html
  */
 
-#ifndef HEADER_AES_LOCL_H
-# define HEADER_AES_LOCL_H
+#ifndef OSSL_CRYPTO_AES_LOCAL_H
+# define OSSL_CRYPTO_AES_LOCAL_H
 
 # include <openssl/e_os2.h>
 # include <stdio.h>
@@ -39,4 +39,4 @@ typedef unsigned char u8;
 /* This controls loop-unrolling in aes_core.c */
 # undef FULL_UNROLL
 
-#endif                          /* !HEADER_AES_LOCL_H */
+#endif                          /* !OSSL_CRYPTO_AES_LOCAL_H */
diff --git a/crypto/arm_arch.h b/crypto/arm_arch.h
index f11b543df64f0ca5edbff10eff5cda19c8c1e571..8b7105571d78a4b6e62bf4ca84d8f706074b5ce5 100644
--- a/crypto/arm_arch.h
+++ b/crypto/arm_arch.h
@@ -7,8 +7,8 @@
  * https://www.openssl.org/source/license.html
  */
 
-#ifndef __ARM_ARCH_H__
-# define __ARM_ARCH_H__
+#ifndef OSSL_CRYPTO_ARM_ARCH_H
+# define OSSL_CRYPTO_ARM_ARCH_H
 
 # if !defined(__ARM_ARCH__)
 #  if defined(__CC_ARM)
diff --git a/crypto/async/arch/async_posix.h b/crypto/async/arch/async_posix.h
index 62449fe60e04ff54c0a2500d7292c98953da5735..873c0316ddf3f359799875c0929ca010e14fd38d 100644
--- a/crypto/async/arch/async_posix.h
+++ b/crypto/async/arch/async_posix.h
@@ -7,8 +7,8 @@
  * https://www.openssl.org/source/license.html
  */
 
-#ifndef OPENSSL_ASYNC_ARCH_ASYNC_POSIX_H
-#define OPENSSL_ASYNC_ARCH_ASYNC_POSIX_H
+#ifndef OSSL_CRYPTO_ASYNC_POSIX_H
+#define OSSL_CRYPTO_ASYNC_POSIX_H
 #include <openssl/e_os2.h>
 
 #if defined(OPENSSL_SYS_UNIX) \
@@ -55,4 +55,4 @@ void async_fibre_free(async_fibre *fibre);
 
 # endif
 #endif
-#endif /* OPENSSL_ASYNC_ARCH_ASYNC_POSIX_H */
+#endif /* OSSL_CRYPTO_ASYNC_POSIX_H */
diff --git a/crypto/bf/bf_local.h b/crypto/bf/bf_local.h
index b1a415e5132c1fc9be67f5b27195722b6ef729e3..8c76976fa4d924eaba71c5bcc1541df5e23b9eb1 100644
--- a/crypto/bf/bf_local.h
+++ b/crypto/bf/bf_local.h
@@ -7,8 +7,8 @@
  * https://www.openssl.org/source/license.html
  */
 
-#ifndef HEADER_BF_LOCL_H
-# define HEADER_BF_LOCL_H
+#ifndef OSSL_CRYPTO_BF_LOCAL_H
+# define OSSL_CRYPTO_BF_LOCAL_H
 # include <openssl/opensslconf.h>
 
 /* NOTE - c is not incremented as per n2l */
diff --git a/crypto/bio/bio_local.h b/crypto/bio/bio_local.h
index 2ec1ef51cdeef7e978589ffd2fae3ad70d276604..8b2122129396d43a5d5bf5feb21187ff89aefe27 100644
--- a/crypto/bio/bio_local.h
+++ b/crypto/bio/bio_local.h
@@ -27,7 +27,7 @@
  * For clarity, we check for internal/cryptlib.h since it's a common header
  * that also includes bio.h.
  */
-# ifdef HEADER_CRYPTLIB_H
+# ifdef OSSL_INTERNAL_CRYPTLIB_H
 #  error internal/cryptlib.h included before bio_local.h
 # endif
 # ifdef HEADER_BIO_H
diff --git a/crypto/bn/bn_local.h b/crypto/bn/bn_local.h
index 5e895b0cd12e34fdbc84df9f95a4f19d3a34d964..37228104c640f496e40fae903605d54ded887854 100644
--- a/crypto/bn/bn_local.h
+++ b/crypto/bn/bn_local.h
@@ -7,8 +7,8 @@
  * https://www.openssl.org/source/license.html
  */
 
-#ifndef HEADER_BN_LCL_H
-# define HEADER_BN_LCL_H
+#ifndef OSSL_CRYPTO_BN_LOCAL_H
+# define OSSL_CRYPTO_BN_LOCAL_H
 
 /*
  * The EDK2 build doesn't use bn_conf.h; it sets THIRTY_TWO_BIT or
diff --git a/crypto/bn/rsaz_exp.h b/crypto/bn/rsaz_exp.h
index c5864f8aaa8c9d25bed6a50511ed23d19225d30b..88f65a4bae46129128ec34ce4fcadf6895e20f9e 100644
--- a/crypto/bn/rsaz_exp.h
+++ b/crypto/bn/rsaz_exp.h
@@ -12,8 +12,8 @@
  * (2) University of Haifa, Israel
  */
 
-#ifndef RSAZ_EXP_H
-# define RSAZ_EXP_H
+#ifndef OSSL_CRYPTO_BN_RSAZ_EXP_H
+# define OSSL_CRYPTO_BN_RSAZ_EXP_H
 
 # undef RSAZ_ENABLED
 # if defined(OPENSSL_BN_ASM_MONT) && \
diff --git a/crypto/camellia/cmll_local.h b/crypto/camellia/cmll_local.h
index 6403b390d82d474a4b8ed97f14d72e0a50e8ddd3..d16baa55facc460756da5b2a02406fa8ae68a65c 100644
--- a/crypto/camellia/cmll_local.h
+++ b/crypto/camellia/cmll_local.h
@@ -22,8 +22,8 @@
  * to the OpenSSL project.
  */
 
-#ifndef HEADER_CAMELLIA_LOCL_H
-# define HEADER_CAMELLIA_LOCL_H
+#ifndef OSSL_CRYPTO_CAMELLIA_CMLL_LOCAL_H
+# define OSSL_CRYPTO_CAMELLIA_CMLL_LOCAL_H
 
 typedef unsigned int u32;
 typedef unsigned char u8;
@@ -40,4 +40,4 @@ void Camellia_EncryptBlock(int keyBitLength, const u8 plaintext[],
                            const KEY_TABLE_TYPE keyTable, u8 ciphertext[]);
 void Camellia_DecryptBlock(int keyBitLength, const u8 ciphertext[],
                            const KEY_TABLE_TYPE keyTable, u8 plaintext[]);
-#endif                          /* #ifndef HEADER_CAMELLIA_LOCL_H */
+#endif                          /* #ifndef OSSL_CRYPTO_CAMELLIA_CMLL_LOCAL_H */
diff --git a/crypto/cms/cms_local.h b/crypto/cms/cms_local.h
index 68aa01271bc2e71d02d797c0183f9d8eaf73fc68..a0ce4448f6036e54da858901857cde3e8196ead2 100644
--- a/crypto/cms/cms_local.h
+++ b/crypto/cms/cms_local.h
@@ -7,8 +7,8 @@
  * https://www.openssl.org/source/license.html
  */
 
-#ifndef HEADER_CMS_LCL_H
-# define HEADER_CMS_LCL_H
+#ifndef OSSL_CRYPTO_CMS_LOCAL_H
+# define OSSL_CRYPTO_CMS_LOCAL_H
 
 # include <openssl/x509.h>
 
diff --git a/crypto/des/des_local.h b/crypto/des/des_local.h
index f401e6f3ebe89f1e8bd8c1ed78402f4bcc7ca0ec..0f58a1c9ae2e8f66518326501279398498ea244b 100644
--- a/crypto/des/des_local.h
+++ b/crypto/des/des_local.h
@@ -7,8 +7,8 @@
  * https://www.openssl.org/source/license.html
  */
 
-#ifndef HEADER_DES_LOCL_H
-# define HEADER_DES_LOCL_H
+#ifndef OSSL_CRYPTO_DES_LOCAL_H
+# define OSSL_CRYPTO_DES_LOCAL_H
 
 # include <openssl/e_os2.h>
 
diff --git a/crypto/ec/curve448/arch_32/arch_intrinsics.h b/crypto/ec/curve448/arch_32/arch_intrinsics.h
index c464108a9dbdbe9d0d8856e74587a9a06d67a0b8..5f6389863d151e985b23d9fd7d7e1da608f62c6d 100644
--- a/crypto/ec/curve448/arch_32/arch_intrinsics.h
+++ b/crypto/ec/curve448/arch_32/arch_intrinsics.h
@@ -10,8 +10,8 @@
  * Originally written by Mike Hamburg
  */
 
-#ifndef HEADER_ARCH_32_ARCH_INTRINSICS_H
-# define HEADER_ARCH_32_ARCH_INTRINSICS_H
+#ifndef OSSL_CRYPTO_EC_CURVE448_ARCH_32_INTRINSICS_H
+# define OSSL_CRYPTO_EC_CURVE448_ARCH_32_INTRINSICS_H
 
 #include "internal/constant_time.h"
 
@@ -24,4 +24,4 @@ static ossl_inline uint64_t widemul(uint32_t a, uint32_t b)
     return ((uint64_t)a) * b;
 }
 
-#endif                          /* HEADER_ARCH_32_ARCH_INTRINSICS_H */
+#endif                          /* OSSL_CRYPTO_EC_CURVE448_ARCH_32_INTRINSICS_H */
diff --git a/crypto/ec/curve448/arch_32/f_impl.h b/crypto/ec/curve448/arch_32/f_impl.h
index bbde84a0389755b66b46843073b678216aafb3bd..e1ddddaee08da760bb52023b93c402f346658f2c 100644
--- a/crypto/ec/curve448/arch_32/f_impl.h
+++ b/crypto/ec/curve448/arch_32/f_impl.h
@@ -10,8 +10,8 @@
  * Originally written by Mike Hamburg
  */
 
-#ifndef HEADER_ARCH_32_F_IMPL_H
-# define HEADER_ARCH_32_F_IMPL_H
+#ifndef OSSL_CRYPTO_EC_CURVE448_ARCH_32_F_IMPL_H
+# define OSSL_CRYPTO_EC_CURVE448_ARCH_32_F_IMPL_H
 
 # define GF_HEADROOM 2
 # define LIMB(x) ((x) & ((1 << 28) - 1)), ((x) >> 28)
@@ -57,4 +57,4 @@ void gf_weak_reduce(gf a)
     a->limb[0] = (a->limb[0] & mask) + tmp;
 }
 
-#endif                  /* HEADER_ARCH_32_F_IMPL_H */
+#endif                  /* OSSL_CRYPTO_EC_CURVE448_ARCH_32_F_IMPL_H */
diff --git a/crypto/ec/curve448/curve448_local.h b/crypto/ec/curve448/curve448_local.h
index 2bc3bd84c86d02fc16744e38ab46a4b6f25de2d1..b27770661f8917432382d16b1479a74b7276f5e9 100644
--- a/crypto/ec/curve448/curve448_local.h
+++ b/crypto/ec/curve448/curve448_local.h
@@ -6,8 +6,8 @@
  * in the file LICENSE in the source distribution or at
  * https://www.openssl.org/source/license.html
  */
-#ifndef HEADER_CURVE448_LCL_H
-# define HEADER_CURVE448_LCL_H
+#ifndef OSSL_CRYPTO_EC_CURVE448_LOCAL_H
+# define OSSL_CRYPTO_EC_CURVE448_LOCAL_H
 # include "curve448utils.h"
 
 int X448(uint8_t out_shared_key[56], const uint8_t private_key[56],
@@ -35,4 +35,4 @@ int ED448ph_verify(const uint8_t hash[64], const uint8_t signature[114],
 int ED448_public_from_private(uint8_t out_public_key[57],
                               const uint8_t private_key[57]);
 
-#endif              /* HEADER_CURVE448_LCL_H */
+#endif              /* OSSL_CRYPTO_EC_CURVE448_LOCAL_H */
diff --git a/crypto/ec/curve448/curve448utils.h b/crypto/ec/curve448/curve448utils.h
index 9032bb4f730ada1a25e1aeeae6f31801f65258fd..86c258e745e4b8f43f275efbcfaa213a85bceaa3 100644
--- a/crypto/ec/curve448/curve448utils.h
+++ b/crypto/ec/curve448/curve448utils.h
@@ -10,8 +10,8 @@
  * Originally written by Mike Hamburg
  */
 
-#ifndef HEADER_CURVE448UTILS_H
-# define HEADER_CURVE448UTILS_H
+#ifndef OSSL_CRYPTO_EC_CURVE448UTILS_H
+# define OSSL_CRYPTO_EC_CURVE448UTILS_H
 
 # include <openssl/e_os2.h>
 
diff --git a/crypto/ec/curve448/ed448.h b/crypto/ec/curve448/ed448.h
index 5fe939e8e19daa2f687a5f1c71760466d1886741..c1e5c2832f9bc5946b5e54d3521899f7c14ac7fc 100644
--- a/crypto/ec/curve448/ed448.h
+++ b/crypto/ec/curve448/ed448.h
@@ -10,8 +10,8 @@
  * Originally written by Mike Hamburg
  */
 
-#ifndef HEADER_ED448_H
-# define HEADER_ED448_H
+#ifndef OSSL_CRYPTO_EC_CURVE448_ED448_H
+# define OSSL_CRYPTO_EC_CURVE448_ED448_H
 
 # include "point_448.h"
 
@@ -192,4 +192,4 @@ c448_error_t c448_ed448_convert_private_key_to_x448(
                             uint8_t x[X448_PRIVATE_BYTES],
                             const uint8_t ed[EDDSA_448_PRIVATE_BYTES]);
 
-#endif                          /* HEADER_ED448_H */
+#endif                          /* OSSL_CRYPTO_EC_CURVE448_ED448_H */
diff --git a/crypto/ec/curve448/field.h b/crypto/ec/curve448/field.h
index 8d046da5c601487945d8510a60845ad39164012e..ccd04482d2053f66814bba2f2a92b8fd60c0bcaf 100644
--- a/crypto/ec/curve448/field.h
+++ b/crypto/ec/curve448/field.h
@@ -10,8 +10,8 @@
  * Originally written by Mike Hamburg
  */
 
-#ifndef HEADER_FIELD_H
-# define HEADER_FIELD_H
+#ifndef OSSL_CRYPTO_EC_CURVE448_FIELD_H
+# define OSSL_CRYPTO_EC_CURVE448_FIELD_H
 
 # include "internal/constant_time.h"
 # include <string.h>
@@ -165,4 +165,4 @@ static ossl_inline void gf_cond_swap(gf x, gf_s * RESTRICT y, mask_t swap)
     }
 }
 
-#endif                          /* HEADER_FIELD_H */
+#endif                          /* OSSL_CRYPTO_EC_CURVE448_FIELD_H */
diff --git a/crypto/ec/curve448/point_448.h b/crypto/ec/curve448/point_448.h
index 399f91b9a1d98055516e31780b2115da526a1f3e..93e715fd9c8d822fad18041751daa79222341d56 100644
--- a/crypto/ec/curve448/point_448.h
+++ b/crypto/ec/curve448/point_448.h
@@ -10,8 +10,8 @@
  * Originally written by Mike Hamburg
  */
 
-#ifndef HEADER_POINT_448_H
-# define HEADER_POINT_448_H
+#ifndef OSSL_CRYPTO_EC_CURVE448_POINT_448_H
+# define OSSL_CRYPTO_EC_CURVE448_POINT_448_H
 
 # include "curve448utils.h"
 # include "field.h"
@@ -298,4 +298,4 @@ void curve448_scalar_destroy(curve448_scalar_t scalar);
 /* Overwrite point with zeros. */
 void curve448_point_destroy(curve448_point_t point);
 
-#endif                          /* HEADER_POINT_448_H */
+#endif                          /* OSSL_CRYPTO_EC_CURVE448_POINT_448_H */
diff --git a/crypto/ec/curve448/word.h b/crypto/ec/curve448/word.h
index a48b9e053a5c9e29343ee92b2640ed98955b7d2a..237cc9b63139a67d2d8389d18cbb7fe4065fe0fe 100644
--- a/crypto/ec/curve448/word.h
+++ b/crypto/ec/curve448/word.h
@@ -10,8 +10,8 @@
  * Originally written by Mike Hamburg
  */
 
-#ifndef HEADER_WORD_H
-# define HEADER_WORD_H
+#ifndef OSSL_CRYPTO_EC_CURVE448_WORD_H
+# define OSSL_CRYPTO_EC_CURVE448_WORD_H
 
 # include <string.h>
 # include <assert.h>
@@ -78,4 +78,4 @@ static ossl_inline mask_t bool_to_mask(c448_bool_t m)
     return ret;
 }
 
-#endif                          /* HEADER_WORD_H */
+#endif                          /* OSSL_CRYPTO_EC_CURVE448_WORD_H */
diff --git a/crypto/engine/eng_local.h b/crypto/engine/eng_local.h
index b5f3b502c16bd1bec6a64b821f9316ecb617815e..8ef7172b9f45a15442ed9a0dc14617ca92ff5281 100644
--- a/crypto/engine/eng_local.h
+++ b/crypto/engine/eng_local.h
@@ -8,8 +8,8 @@
  * https://www.openssl.org/source/license.html
  */
 
-#ifndef HEADER_ENGINE_INT_H
-# define HEADER_ENGINE_INT_H
+#ifndef OSSL_CRYPTO_ENGINE_ENG_LOCAL_H
+# define OSSL_CRYPTO_ENGINE_ENG_LOCAL_H
 
 # include "internal/cryptlib.h"
 # include "crypto/engine.h"
@@ -168,4 +168,4 @@ typedef struct st_engine_pile ENGINE_PILE;
 
 DEFINE_LHASH_OF(ENGINE_PILE);
 
-#endif                          /* HEADER_ENGINE_INT_H */
+#endif                          /* OSSL_CRYPTO_ENGINE_ENG_LOCAL_H */
diff --git a/crypto/hmac/hmac_local.h b/crypto/hmac/hmac_local.h
index 8fd8345694a26baf3d79421c05ad872781392ef2..ed855e89a4e2529db9db49526acc844e6a5e53ff 100644
--- a/crypto/hmac/hmac_local.h
+++ b/crypto/hmac/hmac_local.h
@@ -7,8 +7,8 @@
  * https://www.openssl.org/source/license.html
  */
 
-#ifndef HEADER_HMAC_LCL_H
-# define HEADER_HMAC_LCL_H
+#ifndef OSSL_CRYPTO_HMAC_LOCAL_H
+# define OSSL_CRYPTO_HMAC_LOCAL_H
 
 /* The current largest case is for SHA3-224 */
 #define HMAC_MAX_MD_CBLOCK_SIZE     144
diff --git a/crypto/mips_arch.h b/crypto/mips_arch.h
index e18ac07210c5446104caec8ece33256b22ce0d5a..4ae1a1a9339e30d058e7d8b21ca69824b85a9baa 100644
--- a/crypto/mips_arch.h
+++ b/crypto/mips_arch.h
@@ -7,8 +7,8 @@
  * https://www.openssl.org/source/license.html
  */
 
-#ifndef __MIPS_ARCH_H__
-# define __MIPS_ARCH_H__
+#ifndef OSSL_CRYPTO_MIPS_ARCH_H
+# define OSSL_CRYPTO_MIPS_ARCH_H
 
 # if (defined(__mips_smartmips) || defined(_MIPS_ARCH_MIPS32R3) || \
       defined(_MIPS_ARCH_MIPS32R5) || defined(_MIPS_ARCH_MIPS32R6)) \
diff --git a/crypto/ppc_arch.h b/crypto/ppc_arch.h
index 72bd7468745c77af501c51b08dd94a27b53c4b84..e3845e9394ae2825a31794814bb17416e2d54305 100644
--- a/crypto/ppc_arch.h
+++ b/crypto/ppc_arch.h
@@ -7,8 +7,8 @@
  * https://www.openssl.org/source/license.html
  */
 
-#ifndef HEADER_PPC_ARCH_H
-# define HEADER_PPC_ARCH_H
+#ifndef OSSL_CRYPTO_PPC_ARCH_H
+# define OSSL_CRYPTO_PPC_ARCH_H
 
 extern unsigned int OPENSSL_ppccap_P;
 
diff --git a/crypto/rand/rand_local.h b/crypto/rand/rand_local.h
index 306c59f6efa0f6f84957f13f8e7eeb7228b304c1..96fa3cabceabd902f8507757a3b6e4ab52794be0 100644
--- a/crypto/rand/rand_local.h
+++ b/crypto/rand/rand_local.h
@@ -7,8 +7,8 @@
  * https://www.openssl.org/source/license.html
  */
 
-#ifndef HEADER_RAND_LCL_H
-# define HEADER_RAND_LCL_H
+#ifndef OSSL_CRYPTO_RAND_LOCAL_H
+# define OSSL_CRYPTO_RAND_LOCAL_H
 
 # include <openssl/aes.h>
 # include <openssl/evp.h>
diff --git a/crypto/rc4/rc4_local.h b/crypto/rc4/rc4_local.h
index 4380addbccb21e668f103e7d8deb023415656b77..e739be4be793314a52d6d270e61c5639943111cd 100644
--- a/crypto/rc4/rc4_local.h
+++ b/crypto/rc4/rc4_local.h
@@ -7,8 +7,8 @@
  * https://www.openssl.org/source/license.html
  */
 
-#ifndef HEADER_RC4_LOCL_H
-# define HEADER_RC4_LOCL_H
+#ifndef OSSL_CRYPTO_RC4_LOCAL_H
+# define OSSL_CRYPTO_RC4_LOCAL_H
 
 # include <openssl/opensslconf.h>
 # include "internal/cryptlib.h"
diff --git a/crypto/s390x_arch.h b/crypto/s390x_arch.h
index 4a775a927db7627c679cfaae69ac33d8c743a262..4d2cc02eb3d30622b909f68a7f8cb3b246c1cd26 100644
--- a/crypto/s390x_arch.h
+++ b/crypto/s390x_arch.h
@@ -7,8 +7,8 @@
  * https://www.openssl.org/source/license.html
  */
 
-#ifndef S390X_ARCH_H
-# define S390X_ARCH_H
+#ifndef OSSL_CRYPTO_S390X_ARCH_H
+# define OSSL_CRYPTO_S390X_ARCH_H
 
 # ifndef __ASSEMBLER__
 
diff --git a/crypto/seed/seed_local.h b/crypto/seed/seed_local.h
index ac2950d97c2b30283492403f8702e301cdbaebe3..e3681f8bd45550f15bf97ab1f847416cb4f6ea18 100644
--- a/crypto/seed/seed_local.h
+++ b/crypto/seed/seed_local.h
@@ -32,8 +32,8 @@
  * SUCH DAMAGE.
  *
  */
-#ifndef HEADER_SEED_LOCL_H
-# define HEADER_SEED_LOCL_H
+#ifndef OSSL_CRYPTO_SEED_LOCAL_H
+# define OSSL_CRYPTO_SEED_LOCAL_H
 
 # include "openssl/e_os2.h"
 # include <openssl/seed.h>
@@ -109,4 +109,4 @@ typedef unsigned int seed_word;
         (X1) ^= (T0);                            \
         (X2) ^= (T1)
 
-#endif                          /* HEADER_SEED_LOCL_H */
+#endif                          /* OSSL_CRYPTO_SEED_LOCAL_H */
diff --git a/crypto/sparc_arch.h b/crypto/sparc_arch.h
index 99eafb331352e8ef9f33cf0f671295d10ad14af7..c74063be2fa6aceec80d20246d50694292730dda 100644
--- a/crypto/sparc_arch.h
+++ b/crypto/sparc_arch.h
@@ -7,8 +7,8 @@
  * https://www.openssl.org/source/license.html
  */
 
-#ifndef __SPARC_ARCH_H__
-# define __SPARC_ARCH_H__
+#ifndef OSSL_CRYPTO_SPARC_ARCH_H
+# define OSSL_CRYPTO_SPARC_ARCH_H
 
 # define SPARCV9_TICK_PRIVILEGED (1<<0)
 # define SPARCV9_PREFER_FPU      (1<<1)
@@ -115,4 +115,4 @@
         mov     tmp, %o7;
 # endif
 
-#endif                          /* __SPARC_ARCH_H__ */
+#endif                          /* OSSL_CRYPTO_SPARC_ARCH_H */
diff --git a/crypto/ui/ui_local.h b/crypto/ui/ui_local.h
index 19b33b8fc6776f556054ba8df45bf5ebd09aa4c1..8a7dbda147216ff0cf1b943d2d94c1e7acc8c2b1 100644
--- a/crypto/ui/ui_local.h
+++ b/crypto/ui/ui_local.h
@@ -7,8 +7,8 @@
  * https://www.openssl.org/source/license.html
  */
 
-#ifndef HEADER_UI_LOCL_H
-# define HEADER_UI_LOCL_H
+#ifndef OSSL_CRYPTO_UI_LOCAL_H
+# define OSSL_CRYPTO_UI_LOCAL_H
 
 # include <openssl/ui.h>
 # include <openssl/crypto.h>
diff --git a/crypto/x509v3/v3_admis.h b/crypto/x509v3/v3_admis.h
index fa23fc761759f26725ee9c5ec1f5c39600fcc201..ea7632b3708d0b13638e425d5087dd38d785d34b 100644
--- a/crypto/x509v3/v3_admis.h
+++ b/crypto/x509v3/v3_admis.h
@@ -7,8 +7,8 @@
  * https://www.openssl.org/source/license.html
  */
 
-#ifndef HEADER_V3_ADMISSION_H
-# define HEADER_V3_ADMISSION_H
+#ifndef OSSL_CRYPTO_X509V3_V3_ADMIS_H
+# define OSSL_CRYPTO_X509V3_V3_ADMIS_H
 
 struct NamingAuthority_st {
     ASN1_OBJECT* namingAuthorityId;
diff --git a/e_os.h b/e_os.h
index 858bc40cb1fcedcbf77875be472c188a29832850..2f8e3fe34966a2f3f6ae623c090e74c712a51b48 100644
--- a/e_os.h
+++ b/e_os.h
@@ -7,8 +7,8 @@
  * https://www.openssl.org/source/license.html
  */
 
-#ifndef HEADER_E_OS_H
-# define HEADER_E_OS_H
+#ifndef OSSL_E_OS_H
+# define OSSL_E_OS_H
 
 # include <limits.h>
 # include <openssl/opensslconf.h>
diff --git a/engines/e_afalg.h b/engines/e_afalg.h
index 2c03c448d684a479056be9d76b36c187006081ea..3323c898c634444f7703d50cd2197b0dff5e4294 100644
--- a/engines/e_afalg.h
+++ b/engines/e_afalg.h
@@ -7,8 +7,8 @@
  * https://www.openssl.org/source/license.html
  */
 
-#ifndef HEADER_AFALG_H
-# define HEADER_AFALG_H
+#ifndef OSSL_ENGINES_E_AFALG_H
+# define OSSL_ENGINES_E_AFALG_H
 
 # if defined(__GNUC__) && __GNUC__ >= 4 && \
      (!defined(__STDC_VERSION__) || __STDC_VERSION__ < 199901L)
diff --git a/engines/e_afalg_err.h b/engines/e_afalg_err.h
index 3eb1332bbfe465a3268c02e9fc0fa03d23e86c7f..3036443f44706377bf98dfa13767cd24a6c2a066 100644
--- a/engines/e_afalg_err.h
+++ b/engines/e_afalg_err.h
@@ -8,8 +8,8 @@
  * https://www.openssl.org/source/license.html
  */
 
-#ifndef HEADER_AFALGERR_H
-# define HEADER_AFALGERR_H
+#ifndef OSSL_ENGINES_E_AFALG_ERR_H
+# define OSSL_ENGINES_E_AFALG_ERR_H
 
 # define AFALGerr(f, r) ERR_AFALG_error((f), (r), OPENSSL_FILE, OPENSSL_LINE)
 
diff --git a/engines/e_capi_err.h b/engines/e_capi_err.h
index e034c98cae842ef08d523d81d9efb355b157c162..e3a927aa73398dda5898b141d646f98af0eafe04 100644
--- a/engines/e_capi_err.h
+++ b/engines/e_capi_err.h
@@ -8,8 +8,8 @@
  * https://www.openssl.org/source/license.html
  */
 
-#ifndef HEADER_CAPIERR_H
-# define HEADER_CAPIERR_H
+#ifndef OSSL_ENGINES_E_CAPI_ERR_H
+# define OSSL_ENGINES_E_CAPI_ERR_H
 
 # define CAPIerr(f, r) ERR_CAPI_error((f), (r), OPENSSL_FILE, OPENSSL_LINE)
 
diff --git a/engines/e_dasync_err.h b/engines/e_dasync_err.h
index 7c2c0278790b569acf7f401364a7b66d9d109fa0..5b74d8be25f1eff0580ad8c7cf8c17cf51a641d9 100644
--- a/engines/e_dasync_err.h
+++ b/engines/e_dasync_err.h
@@ -8,8 +8,8 @@
  * https://www.openssl.org/source/license.html
  */
 
-#ifndef HEADER_DASYNCERR_H
-# define HEADER_DASYNCERR_H
+#ifndef OSSL_ENGINES_E_DASYNC_ERR_H
+# define OSSL_ENGINES_E_DASYNC_ERR_H
 
 # define DASYNCerr(f, r) ERR_DASYNC_error((f), (r), OPENSSL_FILE, OPENSSL_LINE)
 
diff --git a/engines/e_ossltest_err.h b/engines/e_ossltest_err.h
index e745c1a236d4dbd377d2360c2d8e125f0af30861..8e6535b76c08e631177f1f758903c52f4d9df6bc 100644
--- a/engines/e_ossltest_err.h
+++ b/engines/e_ossltest_err.h
@@ -8,8 +8,8 @@
  * https://www.openssl.org/source/license.html
  */
 
-#ifndef HEADER_OSSLTESTERR_H
-# define HEADER_OSSLTESTERR_H
+#ifndef OSSL_ENGINES_E_OSSLTEST_ERR_H
+# define OSSL_ENGINES_E_OSSLTEST_ERR_H
 
 # define OSSLTESTerr(f, r) ERR_OSSLTEST_error((f), (r), OPENSSL_FILE, OPENSSL_LINE)
 
diff --git a/include/crypto/aria.h b/include/crypto/aria.h
index 355abe5398059b1d9bbed56a013742c88cebad86..03a62950ae41e2ba06eb791bcaac8322ec36d0f9 100644
--- a/include/crypto/aria.h
+++ b/include/crypto/aria.h
@@ -10,8 +10,8 @@
 
  /* Copyright (c) 2017 National Security Research Institute.  All rights reserved. */
 
-#ifndef HEADER_ARIA_H
-# define HEADER_ARIA_H
+#ifndef OSSL_CRYPTO_ARIA_H
+# define OSSL_CRYPTO_ARIA_H
 
 # include <openssl/opensslconf.h>
 
diff --git a/include/crypto/bn.h b/include/crypto/bn.h
index 30be7efe14d8d6d97ce3b246c4d51cee1c8a6858..60afda1dadee0c56eecae294e44d683675eb0872 100644
--- a/include/crypto/bn.h
+++ b/include/crypto/bn.h
@@ -7,8 +7,8 @@
  * https://www.openssl.org/source/license.html
  */
 
-#ifndef HEADER_BN_INT_H
-# define HEADER_BN_INT_H
+#ifndef OSSL_CRYPTO_BN_H
+# define OSSL_CRYPTO_BN_H
 
 # include <openssl/bn.h>
 # include <limits.h>
diff --git a/include/crypto/bn_conf.h.in b/include/crypto/bn_conf.h.in
index ec6e4f6c1b5ec1484f1cc7542f7673413286eb81..b6b9eb743fd37c03b3829565e55fdaef4516354d 100644
--- a/include/crypto/bn_conf.h.in
+++ b/include/crypto/bn_conf.h.in
@@ -8,8 +8,8 @@
  * https://www.openssl.org/source/license.html
  */
 
-#ifndef HEADER_BN_CONF_H
-# define HEADER_BN_CONF_H
+#ifndef OSSL_CRYPTO_BN_CONF_H
+# define OSSL_CRYPTO_BN_CONF_H
 
 /*
  * The contents of this file are not used in the UEFI build, as
diff --git a/include/crypto/chacha.h b/include/crypto/chacha.h
index 67243f2228016621f982ff50c797c088904455ed..4029400a670ccd11a518135f1fa007dd58e948f1 100644
--- a/include/crypto/chacha.h
+++ b/include/crypto/chacha.h
@@ -7,8 +7,8 @@
  * https://www.openssl.org/source/license.html
  */
 
-#ifndef HEADER_CHACHA_H
-#define HEADER_CHACHA_H
+#ifndef OSSL_CRYPTO_CHACHA_H
+#define OSSL_CRYPTO_CHACHA_H
 
 #include <stddef.h>
 
diff --git a/include/crypto/ctype.h b/include/crypto/ctype.h
index 9f3a58339c4ffe715fb2688775fe5d6c73e5769d..81ef8f5cf7e10c6ee071d3408e1c72f083969a9b 100644
--- a/include/crypto/ctype.h
+++ b/include/crypto/ctype.h
@@ -18,8 +18,8 @@
  * throughout the rest of the source code.  Refer to issue #4154 for
  * details.
  */
-#ifndef INTERNAL_CTYPE_H
-# define INTERNAL_CTYPE_H
+#ifndef OSSL_CRYPTO_CTYPE_H
+# define OSSL_CRYPTO_CTYPE_H
 
 # define CTYPE_MASK_lower       0x1
 # define CTYPE_MASK_upper       0x2
diff --git a/include/crypto/dso_conf.h.in b/include/crypto/dso_conf.h.in
index b2ace48a8002be590bbf02511ddc1392bcfc3f4c..57a09b10a259705a4455f5302bd0426bad5a708e 100644
--- a/include/crypto/dso_conf.h.in
+++ b/include/crypto/dso_conf.h.in
@@ -8,8 +8,8 @@
  * https://www.openssl.org/source/license.html
  */
 
-#ifndef HEADER_DSO_CONF_H
-# define HEADER_DSO_CONF_H
+#ifndef OSSL_CRYPTO_DSO_CONF_H
+# define OSSL_CRYPTO_DSO_CONF_H
 {-  # The DSO code currently always implements all functions so that no
     # applications will have to worry about that from a compilation point
     # of view. However, the "method"s may return zero unless that platform
diff --git a/include/crypto/ec.h b/include/crypto/ec.h
index 182c39cc80566e464674b8a42c2437c648b39746..fe52ae704bb9facb89528376cb528a90227b17ba 100644
--- a/include/crypto/ec.h
+++ b/include/crypto/ec.h
@@ -9,8 +9,8 @@
 
 /* Internal EC functions for other submodules: not for application use */
 
-#ifndef HEADER_OSSL_EC_INTERNAL_H
-# define HEADER_OSSL_EC_INTERNAL_H
+#ifndef OSSL_CRYPTO_EC_H
+# define OSSL_CRYPTO_EC_H
 # include <openssl/opensslconf.h>
 
 # ifndef OPENSSL_NO_EC
diff --git a/include/crypto/err.h b/include/crypto/err.h
index 44ac9446275001e0ae3949479c5a9836ff0f22ff..8ab0e5baaa2cf8e463c0e370d68c054de48f5af0 100644
--- a/include/crypto/err.h
+++ b/include/crypto/err.h
@@ -7,8 +7,8 @@
  * https://www.openssl.org/source/license.html
  */
 
-#ifndef INTERNAL_ERR_INT_H
-# define INTERNAL_ERR_INT_H
+#ifndef OSSL_CRYPTO_ERR_H
+# define OSSL_CRYPTO_ERR_H
 
 int err_load_crypto_strings_int(void);
 void err_cleanup(void);
diff --git a/include/crypto/lhash.h b/include/crypto/lhash.h
index 200ba8685da255d910a5883ac45672b31eb30ae1..ab060cce74b4bac34452d9971b4d5fc19c47ec8c 100644
--- a/include/crypto/lhash.h
+++ b/include/crypto/lhash.h
@@ -7,8 +7,8 @@
  * https://www.openssl.org/source/license.html
  */
 
-#ifndef INTERNAL_LHASH_H
-# define INTERNAL_LHASH_H
+#ifndef OSSL_CRYPTO_LHASH_H
+# define OSSL_CRYPTO_LHASH_H
 
 unsigned long openssl_lh_strcasehash(const char *);
 
diff --git a/include/crypto/rand.h b/include/crypto/rand.h
index 10347ab0e374039afcb85648b4d3f4b5129edcbb..5350d3a931198a694a16820b412acabb65065f66 100644
--- a/include/crypto/rand.h
+++ b/include/crypto/rand.h
@@ -15,8 +15,8 @@
  * or in the file LICENSE in the source distribution.
  */
 
-#ifndef HEADER_RAND_INT_H
-# define HEADER_RAND_INT_H
+#ifndef OSSL_CRYPTO_RAND_H
+# define OSSL_CRYPTO_RAND_H
 
 # include <openssl/rand.h>
 
diff --git a/include/crypto/sha.h b/include/crypto/sha.h
index 458a75e89d4a784651e265cf68ab11c44d34d35c..6d15edb9e57e2911292de7bd1de804329f17b47e 100644
--- a/include/crypto/sha.h
+++ b/include/crypto/sha.h
@@ -8,8 +8,8 @@
  * https://www.openssl.org/source/license.html
  */
 
-#ifndef HEADER_INTERNAL_SHA_H
-# define HEADER_INTERNAL_SHA_H
+#ifndef OSSL_CRYPTO_SHA_H
+# define OSSL_CRYPTO_SHA_H
 
 # include <openssl/opensslconf.h>
 
diff --git a/include/crypto/sm2.h b/include/crypto/sm2.h
index 5c5cd4b4f5672578e3473257ba3b057dad2e0b55..76ee80baff19237e6f9eadd1088492418b9556f1 100644
--- a/include/crypto/sm2.h
+++ b/include/crypto/sm2.h
@@ -9,8 +9,8 @@
  * https://www.openssl.org/source/license.html
  */
 
-#ifndef HEADER_SM2_H
-# define HEADER_SM2_H
+#ifndef OSSL_CRYPTO_SM2_H
+# define OSSL_CRYPTO_SM2_H
 # include <openssl/opensslconf.h>
 
 # ifndef OPENSSL_NO_SM2
diff --git a/include/crypto/sm2err.h b/include/crypto/sm2err.h
index 09edfab787f41596062b5657ea6d1de951a9de29..d1c0ee25918c1a14be5688b81fb836ce69f286bb 100644
--- a/include/crypto/sm2err.h
+++ b/include/crypto/sm2err.h
@@ -8,8 +8,8 @@
  * https://www.openssl.org/source/license.html
  */
 
-#ifndef HEADER_SM2ERR_H
-# define HEADER_SM2ERR_H
+#ifndef OSSL_CRYPTO_SM2ERR_H
+# define OSSL_CRYPTO_SM2ERR_H
 
 # ifndef HEADER_SYMHACKS_H
 #  include <openssl/symhacks.h>
diff --git a/include/crypto/sm3.h b/include/crypto/sm3.h
index 27eb471c2831321294ed308e51324d110ecaa4d2..97e7460333313ae485f189a4d3fbf6b4bfe705f7 100644
--- a/include/crypto/sm3.h
+++ b/include/crypto/sm3.h
@@ -8,8 +8,8 @@
  * https://www.openssl.org/source/license.html
  */
 
-#ifndef HEADER_SM3_H
-# define HEADER_SM3_H
+#ifndef OSSL_CRYPTO_SM3_H
+# define OSSL_CRYPTO_SM3_H
 
 # include <openssl/opensslconf.h>
 
diff --git a/include/crypto/sm4.h b/include/crypto/sm4.h
index f1f157ef535162e308edcbae8195d3269791e1ee..abe28f385e0a6fad84a45b42fe9669f583801122 100644
--- a/include/crypto/sm4.h
+++ b/include/crypto/sm4.h
@@ -8,8 +8,8 @@
  * https://www.openssl.org/source/license.html
  */
 
-#ifndef HEADER_SM4_H
-# define HEADER_SM4_H
+#ifndef OSSL_CRYPTO_SM4_H
+# define OSSL_CRYPTO_SM4_H
 
 # include <openssl/opensslconf.h>
 # include <openssl/e_os2.h>
diff --git a/include/crypto/store.h b/include/crypto/store.h
index 81c075b92b844a522b73b1d30a69c1831c63e746..428d3c60e13ea0b991a8c5fb37323aacfff3763d 100644
--- a/include/crypto/store.h
+++ b/include/crypto/store.h
@@ -7,8 +7,8 @@
  * https://www.openssl.org/source/license.html
  */
 
-#ifndef HEADER_STORE_H
-# define HEADER_STORE_H
+#ifndef OSSL_CRYPTO_STORE_H
+# define OSSL_CRYPTO_STORE_H
 
 # include <openssl/bio.h>
 # include <openssl/store.h>
diff --git a/include/internal/conf.h b/include/internal/conf.h
index 29bc9f963c91d24de38f4b393f5453d72a9ea3a3..163fea8de418a179489adad1a1ed4d774f36588a 100644
--- a/include/internal/conf.h
+++ b/include/internal/conf.h
@@ -7,8 +7,8 @@
  * https://www.openssl.org/source/license.html
  */
 
-#ifndef HEADER_INTERNAL_CONF_H
-# define HEADER_INTERNAL_CONF_H
+#ifndef OSSL_INTERNAL_CONF_H
+# define OSSL_INTERNAL_CONF_H
 
 #include <openssl/conf.h>
 
diff --git a/include/internal/constant_time.h b/include/internal/constant_time.h
index 0193a653d4bb1a70e897dad683e3477e2663bf23..6600a1d72aeb00a92821d3eee5dbbf9a80b8cfc8 100644
--- a/include/internal/constant_time.h
+++ b/include/internal/constant_time.h
@@ -7,8 +7,8 @@
  * https://www.openssl.org/source/license.html
  */
 
-#ifndef HEADER_CONSTANT_TIME_LOCL_H
-# define HEADER_CONSTANT_TIME_LOCL_H
+#ifndef OSSL_INTERNAL_CONSTANT_TIME_H
+# define OSSL_INTERNAL_CONSTANT_TIME_H
 
 # include <stdlib.h>
 # include <string.h>
@@ -384,4 +384,4 @@ static ossl_inline void constant_time_lookup(void *out,
  */
 void err_clear_last_constant_time(int clear);
 
-#endif                          /* HEADER_CONSTANT_TIME_LOCL_H */
+#endif                          /* OSSL_INTERNAL_CONSTANT_TIME_H */
diff --git a/include/internal/cryptlib.h b/include/internal/cryptlib.h
index 23e17e5586e8f527924e454260040bd4dff30b6c..6e7291ae41bc35ad4dab4f6df14e859f3d959dd2 100644
--- a/include/internal/cryptlib.h
+++ b/include/internal/cryptlib.h
@@ -7,8 +7,8 @@
  * https://www.openssl.org/source/license.html
  */
 
-#ifndef HEADER_CRYPTLIB_H
-# define HEADER_CRYPTLIB_H
+#ifndef OSSL_INTERNAL_CRYPTLIB_H
+# define OSSL_INTERNAL_CRYPTLIB_H
 
 # include <stdlib.h>
 # include <string.h>
diff --git a/include/internal/dane.h b/include/internal/dane.h
index a1cb5488ba0033e9709db256091deda440f0f25b..7a39bd7d7d46c6bd011744ec82f20adea9964811 100644
--- a/include/internal/dane.h
+++ b/include/internal/dane.h
@@ -7,8 +7,8 @@
  * https://www.openssl.org/source/license.html
  */
 
-#ifndef HEADER_INTERNAL_DANE_H
-#define HEADER_INTERNAL_DANE_H
+#ifndef OSSL_INTERNAL_DANE_H
+#define OSSL_INTERNAL_DANE_H
 
 #include <openssl/safestack.h>
 
@@ -100,4 +100,4 @@ struct ssl_dane_st {
 #define DANETLS_HAS_DANE_TA(dane) ((dane)&&((dane)->umask & DANETLS_DANE_TA_MASK))
 #define DANETLS_HAS_DANE_EE(dane) ((dane)&&((dane)->umask & DANETLS_DANE_EE_MASK))
 
-#endif /* HEADER_INTERNAL_DANE_H */
+#endif /* OSSL_INTERNAL_DANE_H */
diff --git a/include/internal/dso.h b/include/internal/dso.h
index eb5f7d53c7d6fb0fab977b7111cf0cd316789f1e..c57c0c407592783f69cadb20952b44e73f8e5712 100644
--- a/include/internal/dso.h
+++ b/include/internal/dso.h
@@ -7,8 +7,8 @@
  * https://www.openssl.org/source/license.html
  */
 
-#ifndef HEADER_DSO_H
-# define HEADER_DSO_H
+#ifndef OSSL_INTERNAL_DSO_H
+# define OSSL_INTERNAL_DSO_H
 
 # include <openssl/crypto.h>
 # include "internal/dsoerr.h"
diff --git a/include/internal/dsoerr.h b/include/internal/dsoerr.h
index 5f4511c4d6f88906e0b588e7dd184754e15036f8..94d642a22d8c91aa7ab01a7424accbf1410eacc2 100644
--- a/include/internal/dsoerr.h
+++ b/include/internal/dsoerr.h
@@ -8,8 +8,8 @@
  * https://www.openssl.org/source/license.html
  */
 
-#ifndef HEADER_DSOERR_H
-# define HEADER_DSOERR_H
+#ifndef OSSL_INTERNAL_DSOERR_H
+# define OSSL_INTERNAL_DSOERR_H
 
 # ifndef HEADER_SYMHACKS_H
 #  include <openssl/symhacks.h>
diff --git a/include/internal/err.h b/include/internal/err.h
index d46b8bdb29256c925e63a7c71f32a346dbe08e1c..88dde7059157f07d5bdad26f23794f603a5bf045 100644
--- a/include/internal/err.h
+++ b/include/internal/err.h
@@ -7,8 +7,8 @@
  * https://www.openssl.org/source/license.html
  */
 
-#ifndef INTERNAL_ERR_H
-# define INTERNAL_ERR_H
+#ifndef OSSL_INTERNAL_ERR_H
+# define OSSL_INTERNAL_ERR_H
 
 void err_free_strings_int(void);
 
diff --git a/include/internal/nelem.h b/include/internal/nelem.h
index d65a21a9fbef8b57969f72d6035f4b0301027b87..699ef88ee5234a174bcaf6f6b6ab6e78ee416203 100644
--- a/include/internal/nelem.h
+++ b/include/internal/nelem.h
@@ -7,8 +7,8 @@
  * https://www.openssl.org/source/license.html
  */
 
-#ifndef HEADER_NELEM_H
-# define HEADER_NELEM_H
+#ifndef OSSL_INTERNAL_NELEM_H
+# define OSSL_INTERNAL_NELEM_H
 
 # define OSSL_NELEM(x)    (sizeof(x)/sizeof((x)[0]))
 #endif
diff --git a/include/internal/numbers.h b/include/internal/numbers.h
index 31931df3c2fff5969f09b47345fa3ece2866cc94..f5ade5226e5b52c4bb6ab9b70556962dead44815 100644
--- a/include/internal/numbers.h
+++ b/include/internal/numbers.h
@@ -7,8 +7,8 @@
  * https://www.openssl.org/source/license.html
  */
 
-#ifndef HEADER_NUMBERS_H
-# define HEADER_NUMBERS_H
+#ifndef OSSL_INTERNAL_NUMBERS_H
+# define OSSL_INTERNAL_NUMBERS_H
 
 # include <limits.h>
 
diff --git a/include/internal/o_dir.h b/include/internal/o_dir.h
index e7b55e0c18b3aad5329f0499f21d94370d9d0dfd..dafc8dd2e74b8d4e86ff0c07fd4808c1975ba8ed 100644
--- a/include/internal/o_dir.h
+++ b/include/internal/o_dir.h
@@ -36,8 +36,8 @@
  * SUCH DAMAGE.
  */
 
-#ifndef O_DIR_H
-# define O_DIR_H
+#ifndef OSSL_INTERNAL_O_DIR_H
+# define OSSL_INTERNAL_O_DIR_H
 
 typedef struct OPENSSL_dir_context_st OPENSSL_DIR_CTX;
 
diff --git a/include/internal/o_str.h b/include/internal/o_str.h
index 86403c9ee2829a1dd30e21006a0fd6e2484a7173..15c12e820d2ba5965cc2803c27d2e6e14d89be9f 100644
--- a/include/internal/o_str.h
+++ b/include/internal/o_str.h
@@ -7,8 +7,8 @@
  * https://www.openssl.org/source/license.html
  */
 
-#ifndef HEADER_O_STR_H
-# define HEADER_O_STR_H
+#ifndef OSSL_INTERNAL_O_STR_H
+# define OSSL_INTERNAL_O_STR_H
 
 # include <stddef.h>            /* to get size_t */
 
diff --git a/include/internal/refcount.h b/include/internal/refcount.h
index 6e1a840ef1ea6d67fb549412b32e3704863d1894..8fb536eadc07485c8e76088b7fb8e8ae5894be35 100644
--- a/include/internal/refcount.h
+++ b/include/internal/refcount.h
@@ -6,8 +6,8 @@
  * in the file LICENSE in the source distribution or at
  * https://www.openssl.org/source/license.html
  */
-#ifndef HEADER_INTERNAL_REFCOUNT_H
-# define HEADER_INTERNAL_REFCOUNT_H
+#ifndef OSSL_INTERNAL_REFCOUNT_H
+# define OSSL_INTERNAL_REFCOUNT_H
 
 /* Used to checking reference counts, most while doing perl5 stuff :-) */
 # if defined(OPENSSL_NO_STDIO)
diff --git a/include/internal/sockets.h b/include/internal/sockets.h
index 5bb0355f07ed1a820a7e1266273b71da074b6378..39186efef2076df7de1bd170cacf63165ba65e68 100644
--- a/include/internal/sockets.h
+++ b/include/internal/sockets.h
@@ -8,8 +8,8 @@
  */
 
 
-#ifndef HEADER_INTERNAL_SOCKETS
-# define HEADER_INTERNAL_SOCKETS
+#ifndef OSSL_INTERNAL_SOCKETS_H
+# define OSSL_INTERNAL_SOCKETS_H
 
 # if defined(OPENSSL_SYS_VXWORKS) || defined(OPENSSL_SYS_UEFI)
 #  define NO_SYS_PARAM_H
diff --git a/include/internal/sslconf.h b/include/internal/sslconf.h
index d538f8614f586457fe91a5f73cb76f3d35104c17..92c8941d0250c0b8f6c8feee8a411bdeb917fc1a 100644
--- a/include/internal/sslconf.h
+++ b/include/internal/sslconf.h
@@ -7,8 +7,8 @@
  * https://www.openssl.org/source/license.html
  */
 
-#ifndef HEADER_SSLCONF_H
-# define HEADER_SSLCONF_H
+#ifndef OSSL_INTERNAL_SSLCONF_H
+# define OSSL_INTERNAL_SSLCONF_H
 
 typedef struct ssl_conf_cmd_st SSL_CONF_CMD;
 
diff --git a/ssl/packet_local.h b/ssl/packet_local.h
index 860360b8b2317a6c6f0813e3e300b360ab3f3327..1b6c2fb9bc3fafcf4046e2d73c3b30492255652a 100644
--- a/ssl/packet_local.h
+++ b/ssl/packet_local.h
@@ -7,8 +7,8 @@
  * https://www.openssl.org/source/license.html
  */
 
-#ifndef HEADER_PACKET_LOCL_H
-# define HEADER_PACKET_LOCL_H
+#ifndef OSSL_SSL_PACKET_LOCAL_H
+# define OSSL_SSL_PACKET_LOCAL_H
 
 # include <string.h>
 # include <openssl/bn.h>
@@ -871,4 +871,4 @@ unsigned char *WPACKET_get_curr(WPACKET *pkt);
 /* Release resources in a WPACKET if a failure has occurred. */
 void WPACKET_cleanup(WPACKET *pkt);
 
-#endif                          /* HEADER_PACKET_LOCL_H */
+#endif                          /* OSSL_SSL_PACKET_LOCAL_H */
diff --git a/ssl/ssl_local.h b/ssl/ssl_local.h
index ef9e1531666d55236cac8c9f0dd4f8a636063d78..d335df252e065ea41fc8d2b26cd51575d6fc73a6 100644
--- a/ssl/ssl_local.h
+++ b/ssl/ssl_local.h
@@ -9,8 +9,8 @@
  * https://www.openssl.org/source/license.html
  */
 
-#ifndef HEADER_SSL_LOCL_H
-# define HEADER_SSL_LOCL_H
+#ifndef OSSL_SSL_LOCAL_H
+# define OSSL_SSL_LOCAL_H
 
 # include "e_os.h"              /* struct timeval for DTLS */
 # include <stdlib.h>
diff --git a/test/drbg_cavs_data.h b/test/drbg_cavs_data.h
index d673375619d3d5510acf77a7723a7d5f14a7afee..c04b01298dc7714f861a0eb10bca3b4e312d7b0c 100644
--- a/test/drbg_cavs_data.h
+++ b/test/drbg_cavs_data.h
@@ -13,8 +13,8 @@
 
 #include <stddef.h>
 
-#ifndef DRBG_CAVS_DATA_H
-# define DRBG_CAVS_DATA_H
+#ifndef OSSL_TEST_DRBG_CAVS_DATA_H
+# define OSSL_TEST_DRBG_CAVS_DATA_H
 
 enum drbg_kat_type {
     NO_RESEED,
diff --git a/test/ecdsatest.h b/test/ecdsatest.h
index 216e66e277e7c791fc7c777630b5cdf083974ff9..63fe31902582f79f6ea818fa0cbeb35b64574c85 100644
--- a/test/ecdsatest.h
+++ b/test/ecdsatest.h
@@ -7,8 +7,8 @@
  * https://www.openssl.org/source/license.html
  */
 
-#ifndef ECDSATEST_CAVS_H
-# define ECDSATEST_CAVS_H
+#ifndef OSSL_TEST_ECDSATEST_H
+# define OSSL_TEST_ECDSATEST_H
 
 /*-
  * NIST CAVP ECDSA KATs:
@@ -10211,4 +10211,4 @@ static const ecdsa_cavs_kat_t ecdsa_cavs_kats[] = {
      "1c8c4343a8ecbf7c4d4e48f7d76d5658bc027c77086ec8b10097deb307d6"}
 # endif                         /* OPENSSL_NO_EC2M */
 };
-#endif                          /* ECDSATEST_CAVS_H */
+#endif                          /* OSSL_TEST_ECDSATEST_H */
diff --git a/test/handshake_helper.h b/test/handshake_helper.h
index ab6446a490bbc65235cc2a2d03d3aa7429e5c00d..96406dd93e449917a4d6465c4d84c0bc808c3874 100644
--- a/test/handshake_helper.h
+++ b/test/handshake_helper.h
@@ -7,8 +7,8 @@
  * https://www.openssl.org/source/license.html
  */
 
-#ifndef HEADER_HANDSHAKE_HELPER_H
-#define HEADER_HANDSHAKE_HELPER_H
+#ifndef OSSL_TEST_HANDSHAKE_HELPER_H
+#define OSSL_TEST_HANDSHAKE_HELPER_H
 
 #include "ssl_test_ctx.h"
 
@@ -78,4 +78,4 @@ HANDSHAKE_RESULT *do_handshake(SSL_CTX *server_ctx, SSL_CTX *server2_ctx,
                                SSL_CTX *resume_client_ctx,
                                const SSL_TEST_CTX *test_ctx);
 
-#endif  /* HEADER_HANDSHAKE_HELPER_H */
+#endif  /* OSSL_TEST_HANDSHAKE_HELPER_H */
diff --git a/test/ossl_shim/async_bio.h b/test/ossl_shim/async_bio.h
index bb24eadbbf249cf79a182887e57f2d243ba01353..c09e236aefa3cd75c1fe72f95a36d83e2d9b93a3 100644
--- a/test/ossl_shim/async_bio.h
+++ b/test/ossl_shim/async_bio.h
@@ -7,8 +7,8 @@
  * https://www.openssl.org/source/license.html
  */
 
-#ifndef HEADER_ASYNC_BIO
-#define HEADER_ASYNC_BIO
+#ifndef OSSL_TEST_SHIM_ASYNC_BIO_H
+#define OSSL_TEST_SHIM_ASYNC_BIO_H
 
 #include <openssl/base.h>
 #include <openssl/bio.h>
@@ -36,4 +36,4 @@ void AsyncBioAllowWrite(BIO *bio, size_t count);
 void AsyncBioEnforceWriteQuota(BIO *bio, bool enforce);
 
 
-#endif  // HEADER_ASYNC_BIO
+#endif  // OSSL_TEST_SHIM_ASYNC_BIO_H
diff --git a/test/ossl_shim/include/openssl/base.h b/test/ossl_shim/include/openssl/base.h
index f725cd9d45c7f31f1b2b35fddbfa2f8006301c21..a8d47b86aeef6d1789c57a30e61cda36829812c3 100644
--- a/test/ossl_shim/include/openssl/base.h
+++ b/test/ossl_shim/include/openssl/base.h
@@ -7,8 +7,8 @@
  * https://www.openssl.org/source/license.html
  */
 
-#ifndef OPENSSL_HEADER_BASE_H
-#define OPENSSL_HEADER_BASE_H
+#ifndef OSSL_TEST_SHIM_INCLUDE_OPENSSL_BASE_H
+#define OSSL_TEST_SHIM_INCLUDE_OPENSSL_BASE_H
 
 /* Needed for BORINGSSL_MAKE_DELETER */
 # include <openssl/bio.h>
@@ -108,4 +108,4 @@ BORINGSSL_MAKE_DELETER(SSL_SESSION, SSL_SESSION_free)
 }  /* extern C++ */
 
 
-#endif  /* OPENSSL_HEADER_BASE_H */
+#endif  /* OSSL_TEST_SHIM_INCLUDE_OPENSSL_BASE_H */
diff --git a/test/ossl_shim/packeted_bio.h b/test/ossl_shim/packeted_bio.h
index 436cf9082f349e0c22a718a91dc826004179a69b..895bd37952d374c578a115cc4aee5810c94b57ff 100644
--- a/test/ossl_shim/packeted_bio.h
+++ b/test/ossl_shim/packeted_bio.h
@@ -7,8 +7,8 @@
  * https://www.openssl.org/source/license.html
  */
 
-#ifndef HEADER_PACKETED_BIO
-#define HEADER_PACKETED_BIO
+#ifndef OSSL_TEST_SHIM_PACKETED_BIO_H
+#define OSSL_TEST_SHIM_PACKETED_BIO_H
 
 #include <openssl/base.h>
 #include <openssl/bio.h>
@@ -32,4 +32,4 @@ timeval PacketedBioGetClock(const BIO *bio);
 bool PacketedBioAdvanceClock(BIO *bio);
 
 
-#endif  // HEADER_PACKETED_BIO
+#endif  // OSSL_TEST_SHIM_PACKETED_BIO_H
diff --git a/test/ossl_shim/test_config.h b/test/ossl_shim/test_config.h
index b4efa455aebcfa482f8bcacb4567a5a3ea457a20..f95475a42e1304c61e051d20c79e40ee253ec4bd 100644
--- a/test/ossl_shim/test_config.h
+++ b/test/ossl_shim/test_config.h
@@ -7,8 +7,8 @@
  * https://www.openssl.org/source/license.html
  */
 
-#ifndef HEADER_TEST_CONFIG
-#define HEADER_TEST_CONFIG
+#ifndef OSSL_TEST_SHIM_TEST_CONFIG_H
+#define OSSL_TEST_SHIM_TEST_CONFIG_H
 
 #include <string>
 #include <vector>
@@ -85,4 +85,4 @@ struct TestConfig {
 bool ParseConfig(int argc, char **argv, TestConfig *out_config);
 
 
-#endif  // HEADER_TEST_CONFIG
+#endif  // OSSL_TEST_SHIM_TEST_CONFIG_H
diff --git a/test/ssl_test_ctx.h b/test/ssl_test_ctx.h
index 36d73f752c3e4e374c1bf7db2436d8070fa34ea5..7e670c946806bd7f755ec9d87d90d3f2ca6c8d85 100644
--- a/test/ssl_test_ctx.h
+++ b/test/ssl_test_ctx.h
@@ -7,8 +7,8 @@
  * https://www.openssl.org/source/license.html
  */
 
-#ifndef HEADER_SSL_TEST_CTX_H
-#define HEADER_SSL_TEST_CTX_H
+#ifndef OSSL_TEST_SSL_TEST_CTX_H
+#define OSSL_TEST_SSL_TEST_CTX_H
 
 #include <openssl/conf.h>
 #include <openssl/ssl.h>
@@ -250,4 +250,4 @@ SSL_TEST_CTX *SSL_TEST_CTX_new(void);
 
 void SSL_TEST_CTX_free(SSL_TEST_CTX *ctx);
 
-#endif  /* HEADER_SSL_TEST_CTX_H */
+#endif  /* OSSL_TEST_SSL_TEST_CTX_H */
diff --git a/test/ssltestlib.h b/test/ssltestlib.h
index 56e323f5bc34e5c9ea1f465a1ee17e56290a3fb0..17b278219a6e766cb336fca8d11b8d4d6820a1a9 100644
--- a/test/ssltestlib.h
+++ b/test/ssltestlib.h
@@ -7,8 +7,8 @@
  * https://www.openssl.org/source/license.html
  */
 
-#ifndef HEADER_SSLTESTLIB_H
-# define HEADER_SSLTESTLIB_H
+#ifndef OSSL_TEST_SSLTESTLIB_H
+# define OSSL_TEST_SSLTESTLIB_H
 
 # include <openssl/ssl.h>
 
@@ -53,4 +53,4 @@ typedef struct mempacket_st MEMPACKET;
 
 DEFINE_STACK_OF(MEMPACKET)
 
-#endif /* HEADER_SSLTESTLIB_H */
+#endif /* OSSL_TEST_SSLTESTLIB_H */
diff --git a/test/testutil.h b/test/testutil.h
index 2a610d7bffca024c092bc680a54f71187f651aca..575be955b55737580c5f85b9466de272ef77c5ea 100644
--- a/test/testutil.h
+++ b/test/testutil.h
@@ -7,8 +7,8 @@
  * https://www.openssl.org/source/license.html
  */
 
-#ifndef HEADER_TESTUTIL_H
-# define HEADER_TESTUTIL_H
+#ifndef OSSL_TESTUTIL_H
+# define OSSL_TESTUTIL_H
 
 #include <stdarg.h>
 
@@ -465,4 +465,4 @@ void test_random_seed(uint32_t sd);
 /* Create a file path from a directory and a filename */
 char *test_mk_file_path(const char *dir, const char *file);
 
-#endif                          /* HEADER_TESTUTIL_H */
+#endif                          /* OSSL_TESTUTIL_H */
diff --git a/test/testutil/output.h b/test/testutil/output.h
index 8e2b2a340ade6621bedb38d9fc20b6f8aa9724d7..f5be69e662068542967f22f424742f7801079503 100644
--- a/test/testutil/output.h
+++ b/test/testutil/output.h
@@ -7,8 +7,8 @@
  * https://www.openssl.org/source/license.html
  */
 
-#ifndef HEADER_TU_OUTPUT_H
-# define HEADER_TU_OUTPUT_H
+#ifndef OSSL_TESTUTIL_OUTPUT_H
+# define OSSL_TESTUTIL_OUTPUT_H
 
 #include <stdarg.h>
 
@@ -29,4 +29,4 @@ int test_flush_stderr(void);
 int test_printf_stdout(const char *fmt, ...);
 int test_printf_stderr(const char *fmt, ...);
 
-#endif                          /* HEADER_TU_OUTPUT_H */
+#endif                          /* OSSL_TESTUTIL_OUTPUT_H */
diff --git a/util/mkerr.pl b/util/mkerr.pl
index df085fb3dbdf059bcf180a4864fb56ef31a94863..dc652e0a0d42665f25e215270c79013cec72b885 100755
--- a/util/mkerr.pl
+++ b/util/mkerr.pl
@@ -450,8 +450,8 @@ foreach my $lib ( keys %errorfile ) {
  * https://www.openssl.org/source/license.html
  */
 
-#ifndef HEADER_${lib}ERR_H
-# define HEADER_${lib}ERR_H
+#ifndef OPENSSL_${lib}ERR_H
+# define OPENSSL_${lib}ERR_H
 
 # include <openssl/symhacks.h>