diff --git a/crypto/sm2/sm2_za.c b/crypto/sm2/sm2_za.c
index a9560c3c04b4a924b42fef85d2e279231544ab91..94d0dac02fb90595c9da7adc9469a1de55236b76 100644
--- a/crypto/sm2/sm2_za.c
+++ b/crypto/sm2/sm2_za.c
@@ -15,6 +15,7 @@
 #include <openssl/evp.h>
 #include <openssl/bn.h>
 #include <string.h>
+#include "internal/numbers.h"
 
 int sm2_compute_userid_digest(uint8_t *out,
                               const EVP_MD *digest,