diff --git a/library/spdm_crypt_lib/libspdm_crypt_hmac.c b/library/spdm_crypt_lib/libspdm_crypt_hmac.c
index 56f8b0efeac..9ea14f3ea7b 100644
--- a/library/spdm_crypt_lib/libspdm_crypt_hmac.c
+++ b/library/spdm_crypt_lib/libspdm_crypt_hmac.c
@@ -14,53 +14,53 @@ void *libspdm_hmac_new(uint32_t base_hash_algo)
         return libspdm_hmac_sha256_new();
 #else
         LIBSPDM_ASSERT(false);
-        return false;
+        return NULL;
 #endif
     case SPDM_ALGORITHMS_BASE_HASH_ALGO_TPM_ALG_SHA_384:
 #if LIBSPDM_SHA384_SUPPORT
         return libspdm_hmac_sha384_new();
 #else
         LIBSPDM_ASSERT(false);
-        return false;
+        return NULL;
 #endif
     case SPDM_ALGORITHMS_BASE_HASH_ALGO_TPM_ALG_SHA_512:
 #if LIBSPDM_SHA512_SUPPORT
         return libspdm_hmac_sha512_new();
 #else
         LIBSPDM_ASSERT(false);
-        return false;
+        return NULL;
 #endif
     case SPDM_ALGORITHMS_BASE_HASH_ALGO_TPM_ALG_SHA3_256:
 #if LIBSPDM_SHA3_256_SUPPORT
         return libspdm_hmac_sha3_256_new();
 #else
         LIBSPDM_ASSERT(false);
-        return false;
+        return NULL;
 #endif
     case SPDM_ALGORITHMS_BASE_HASH_ALGO_TPM_ALG_SHA3_384:
 #if LIBSPDM_SHA3_384_SUPPORT
         return libspdm_hmac_sha3_384_new();
 #else
         LIBSPDM_ASSERT(false);
-        return false;
+        return NULL;
 #endif
     case SPDM_ALGORITHMS_BASE_HASH_ALGO_TPM_ALG_SHA3_512:
 #if LIBSPDM_SHA3_512_SUPPORT
         return libspdm_hmac_sha3_512_new();
 #else
         LIBSPDM_ASSERT(false);
-        return false;
+        return NULL;
 #endif
     case SPDM_ALGORITHMS_BASE_HASH_ALGO_TPM_ALG_SM3_256:
 #if LIBSPDM_SM3_256_SUPPORT
         return libspdm_hmac_sm3_256_new();
 #else
         LIBSPDM_ASSERT(false);
-        return false;
+        return NULL;
 #endif
     default:
         LIBSPDM_ASSERT(false);
-        return false;
+        return NULL;
     }
 }