diff --git a/crypto/ct/ct_oct.c b/crypto/ct/ct_oct.c
index d9fa68afa852f78156d7c75944909041cb772b00..620edab0388dc2203870652485217e5e91d90bc1 100644
--- a/crypto/ct/ct_oct.c
+++ b/crypto/ct/ct_oct.c
@@ -442,7 +442,7 @@ STACK_OF(SCT) *d2i_SCT_LIST(STACK_OF(SCT) **a, const unsigned char **pp,
     return sk;
 }
 
-int i2d_SCT_LIST(STACK_OF(SCT) *a, unsigned char **out)
+int i2d_SCT_LIST(const STACK_OF(SCT) *a, unsigned char **out)
 {
     ASN1_OCTET_STRING oct;
     int len;
diff --git a/include/openssl/ct.h b/include/openssl/ct.h
index 98b2231400bcf1d1bdc656da1255a6c70f56ae2e..7ac8887519e30de1df98f0bf5203c47b4394ac70 100644
--- a/include/openssl/ct.h
+++ b/include/openssl/ct.h
@@ -414,7 +414,7 @@ STACK_OF(SCT) *o2i_SCT_LIST(STACK_OF(SCT) **a, const unsigned char **pp,
  * Returns < 0 on error, >= 0 indicating bytes written (or would have been)
  * on success.
  */
-__owur int i2d_SCT_LIST(STACK_OF(SCT) *a, unsigned char **pp);
+__owur int i2d_SCT_LIST(const STACK_OF(SCT) *a, unsigned char **pp);
 
 /*
  * Parses an SCT list in DER format and returns it.