diff --git a/ext/mysqli/mysqli.c b/ext/mysqli/mysqli.c
index 707a3010450..d1588f14398 100644
--- a/ext/mysqli/mysqli.c
+++ b/ext/mysqli/mysqli.c
@@ -1152,7 +1152,7 @@ void php_mysqli_fetch_into_hash_aux(zval *return_value, MYSQL_RES * result, zend
 {
 #if !defined(MYSQLI_USE_MYSQLND)
 	MYSQL_ROW row;
-	unsigned int	i;
+	unsigned int	i, num_fields;
 	MYSQL_FIELD		*fields;
 	zend_ulong	*field_len;
 
@@ -1166,8 +1166,9 @@ void php_mysqli_fetch_into_hash_aux(zval *return_value, MYSQL_RES * result, zend
 
 	array_init(return_value);
 	field_len = mysql_fetch_lengths(result);
+	num_fields = mysql_num_fields(result);
 
-	for (i = 0; i < mysql_num_fields(result); i++) {
+	for (i = 0; i < num_fields; i++) {
 		if (row[i]) {
 			zval res;
 
diff --git a/ext/mysqli/mysqli_api.c b/ext/mysqli/mysqli_api.c
index 03a39d7e2ea..de1d806f0f5 100644
--- a/ext/mysqli/mysqli_api.c
+++ b/ext/mysqli/mysqli_api.c
@@ -1210,7 +1210,7 @@ PHP_FUNCTION(mysqli_fetch_fields)
 	zval		*mysql_result;
 	zval		obj;
 
-	unsigned int i;
+	unsigned int i, num_fields;
 
 	if (zend_parse_method_parameters(ZEND_NUM_ARGS(), getThis(), "O", &mysql_result, mysqli_result_class_entry) == FAILURE) {
 		return;
@@ -1219,8 +1219,9 @@ PHP_FUNCTION(mysqli_fetch_fields)
 	MYSQLI_FETCH_RESOURCE(result, MYSQL_RES *, mysql_result, "mysqli_result", MYSQLI_STATUS_VALID);
 
 	array_init(return_value);
+	num_fields = mysql_num_fields(result);
 
-	for (i = 0; i < mysql_num_fields(result); i++) {
+	for (i = 0; i < num_fields; i++) {
 		const MYSQL_FIELD *field = mysql_fetch_field_direct(result, i);
 
 		object_init(&obj);
@@ -1266,7 +1267,7 @@ PHP_FUNCTION(mysqli_fetch_lengths)
 {
 	MYSQL_RES		*result;
 	zval			*mysql_result;
-	unsigned int	i;
+	unsigned int	i, num_fields;
 #if defined(MYSQLI_USE_MYSQLND)
 	const size_t	*ret;
 #else
@@ -1284,8 +1285,9 @@ PHP_FUNCTION(mysqli_fetch_lengths)
 	}
 
 	array_init(return_value);
+	num_fields = mysql_num_fields(result);
 
-	for (i = 0; i < mysql_num_fields(result); i++) {
+	for (i = 0; i < num_fields; i++) {
 		add_index_long(return_value, i, ret[i]);
 	}
 }
diff --git a/win32/sendmail.c b/win32/sendmail.c
index c71ab2201fa..62d710589de 100644
--- a/win32/sendmail.c
+++ b/win32/sendmail.c
@@ -677,8 +677,12 @@ static int PostHeader(char *RPath, char *Subject, char *mailTo, char *xheaders)
 	size_t i;
 
 	if (xheaders) {
+		size_t headers_lc_len;
+
 		headers_lc = estrdup(xheaders);
-		for (i = 0; i < strlen(headers_lc); i++) {
+		headers_lc_len = strlen(headers_lc);
+
+		for (i = 0; i < headers_lc_len; i++) {
 			headers_lc[i] = tolower(headers_lc[i]);
 		}
 	}