diff --git a/include/gmssl/aead.h b/include/gmssl/aead.h
index ff24ce71..01f0ddf1 100644
--- a/include/gmssl/aead.h
+++ b/include/gmssl/aead.h
@@ -85,7 +85,9 @@ typedef struct {
 
 #define SM4_GCM_KEY_SIZE 16
 #define SM4_GCM_MIN_IV_SIZE 1
+#define SM4_GCM_DEFAULT_IV_SIZE 12
 #define SM4_GCM_MAX_IV_SIZE 64
+#define SM4_GCM_DEFAULT_TAG_SIZE 16
 
 _gmssl_export int sm4_gcm_encrypt_init(SM4_GCM_CTX *ctx,
 	const uint8_t *key, size_t keylen, const uint8_t *iv, size_t ivlen,