diff --git a/include/gmssl/x509.h b/include/gmssl/x509.h
index 03b6193e..759f5991 100644
--- a/include/gmssl/x509.h
+++ b/include/gmssl/x509.h
@@ -144,13 +144,13 @@ Example:
           SEQUENCE LEN OID=commonNmame, String=ABC
 */
 int x509_name_add_rdn(uint8_t *d, size_t *dlen, size_t maxlen, int oid, int tag, const uint8_t *val, size_t vlen, const uint8_t *more, size_t mlen);
-int x509_name_add_country_name(uint8_t *d, size_t *dlen, int maxlen, const char val[2] ); // val: PrintableString SIZE(2)
-int x509_name_add_state_or_province_name(uint8_t *d, size_t *dlen, int maxlen, int tag, const uint8_t *val, size_t vlen);
-int x509_name_add_locality_name(uint8_t *d, size_t *dlen, int maxlen, int tag, const uint8_t *val, size_t vlen);
-int x509_name_add_organization_name(uint8_t *d, size_t *dlen, int maxlen, int tag, const uint8_t *val, size_t vlen);
-int x509_name_add_organizational_unit_name(uint8_t *d, size_t *dlen, int maxlen, int tag, const uint8_t *val, size_t vlen);
-int x509_name_add_common_name(uint8_t *d, size_t *dlen, int maxlen, int tag, const uint8_t *val, size_t vlen);
-int x509_name_add_domain_component(uint8_t *d, size_t *dlen, int maxlen, const char *val, size_t vlen); // val: IA5String
+int x509_name_add_country_name(uint8_t *d, size_t *dlen, size_t maxlen, const char val[2] ); // val: PrintableString SIZE(2)
+int x509_name_add_state_or_province_name(uint8_t *d, size_t *dlen, size_t maxlen, int tag, const uint8_t *val, size_t vlen);
+int x509_name_add_locality_name(uint8_t *d, size_t *dlen, size_t maxlen, int tag, const uint8_t *val, size_t vlen);
+int x509_name_add_organization_name(uint8_t *d, size_t *dlen, size_t maxlen, int tag, const uint8_t *val, size_t vlen);
+int x509_name_add_organizational_unit_name(uint8_t *d, size_t *dlen, size_t maxlen, int tag, const uint8_t *val, size_t vlen);
+int x509_name_add_common_name(uint8_t *d, size_t *dlen, size_t maxlen, int tag, const uint8_t *val, size_t vlen);
+int x509_name_add_domain_component(uint8_t *d, size_t *dlen, size_t maxlen, const char *val, size_t vlen); // val: IA5String
 
 int x509_name_set(uint8_t *d, size_t *dlen, size_t maxlen,
 	const char *country, const char *state, const char *locality,
diff --git a/src/asn1.c b/src/asn1.c
index 32716f27..b7a77ecd 100644
--- a/src/asn1.c
+++ b/src/asn1.c
@@ -460,7 +460,6 @@ int asn1_integer_to_der_ex(int tag, const uint8_t *a, size_t alen, uint8_t **out
 
 int asn1_int_to_der_ex(int tag, int a, uint8_t **out, size_t *outlen)
 {
-	int i;
 	uint8_t buf[4] = {0};
 	size_t len = 0;
 
diff --git a/src/sm2_alg.c b/src/sm2_alg.c
index 7d57e74e..8042aaf1 100644
--- a/src/sm2_alg.c
+++ b/src/sm2_alg.c
@@ -1,4 +1,4 @@
-/*
+/*
  *  Copyright 2014-2022 The GmSSL Project. All Rights Reserved.
  *
  *  Licensed under the Apache License, Version 2.0 (the License); you may
@@ -219,8 +219,9 @@ int sm2_bn_print(FILE *fp, int fmt, int ind, const char *label, const SM2_BN a)
 void sm2_bn_to_bits(const SM2_BN a, char bits[256])
 {
 	int i, j;
+	uint64_t w;
 	for (i = 7; i >= 0; i--) {
-		uint32_t w = a[i];
+		w = a[i];
 		for (j = 0; j < 32; j++) {
 			*bits++ = (w & 0x80000000) ? '1' : '0';
 			w <<= 1;
diff --git a/src/x509_cer.c b/src/x509_cer.c
index 2edcf606..a81d726d 100644
--- a/src/x509_cer.c
+++ b/src/x509_cer.c
@@ -415,7 +415,7 @@ int x509_name_add_rdn(uint8_t *d, size_t *dlen, size_t maxlen,
 	return 1;
 }
 
-int x509_name_add_country_name(uint8_t *d, size_t *dlen, int maxlen, const char val[2])
+int x509_name_add_country_name(uint8_t *d, size_t *dlen, size_t maxlen, const char val[2])
 {
 	int ret;
 	ret = x509_name_add_rdn(d, dlen, maxlen,
@@ -424,7 +424,7 @@ int x509_name_add_country_name(uint8_t *d, size_t *dlen, int maxlen, const char
 	return ret;
 }
 
-int x509_name_add_state_or_province_name(uint8_t *d, size_t *dlen, int maxlen,
+int x509_name_add_state_or_province_name(uint8_t *d, size_t *dlen, size_t maxlen,
 	int tag, const uint8_t *val, size_t vlen)
 {
 	int ret;
@@ -433,7 +433,7 @@ int x509_name_add_state_or_province_name(uint8_t *d, size_t *dlen, int maxlen,
 	return ret;
 }
 
-int x509_name_add_locality_name(uint8_t *d, size_t *dlen, int maxlen,
+int x509_name_add_locality_name(uint8_t *d, size_t *dlen, size_t maxlen,
 	int tag, const uint8_t *val, size_t vlen)
 {
 	int ret;
@@ -442,7 +442,7 @@ int x509_name_add_locality_name(uint8_t *d, size_t *dlen, int maxlen,
 	return ret;
 }
 
-int x509_name_add_organization_name(uint8_t *d, size_t *dlen, int maxlen,
+int x509_name_add_organization_name(uint8_t *d, size_t *dlen, size_t maxlen,
 	int tag, const uint8_t *val, size_t vlen)
 {
 	int ret;
@@ -451,7 +451,7 @@ int x509_name_add_organization_name(uint8_t *d, size_t *dlen, int maxlen,
 	return ret;
 }
 
-int x509_name_add_organizational_unit_name(uint8_t *d, size_t *dlen, int maxlen,
+int x509_name_add_organizational_unit_name(uint8_t *d, size_t *dlen, size_t maxlen,
 	int tag, const uint8_t *val, size_t vlen)
 {
 	int ret;
@@ -460,7 +460,7 @@ int x509_name_add_organizational_unit_name(uint8_t *d, size_t *dlen, int maxlen,
 	return ret;
 }
 
-int x509_name_add_common_name(uint8_t *d, size_t *dlen, int maxlen,
+int x509_name_add_common_name(uint8_t *d, size_t *dlen, size_t maxlen,
 	int tag, const uint8_t *val, size_t vlen)
 {
 	int ret;
@@ -469,7 +469,7 @@ int x509_name_add_common_name(uint8_t *d, size_t *dlen, int maxlen,
 	return ret;
 }
 
-int x509_name_add_domain_component(uint8_t *d, size_t *dlen, int maxlen,
+int x509_name_add_domain_component(uint8_t *d, size_t *dlen, size_t maxlen,
 	const char *val, size_t vlen)
 {
 	int ret;