diff --git a/ext/kernel/string.c b/ext/kernel/string.c
index d4456af1a40..d9d70ec23cc 100644
--- a/ext/kernel/string.c
+++ b/ext/kernel/string.c
@@ -389,6 +389,9 @@ int phalcon_memnstr_str(const zval *haystack, char *needle, unsigned int needle_
  */
 void phalcon_fast_strpos(zval *return_value, const zval *haystack, const zval *needle) {
 
+#if PHP_VERSION_ID >= 50600
+	const
+#endif
 	char *found = NULL;
 
 	if (unlikely(Z_TYPE_P(haystack) != IS_STRING || Z_TYPE_P(needle) != IS_STRING)) {
@@ -418,6 +421,9 @@ void phalcon_fast_strpos(zval *return_value, const zval *haystack, const zval *n
  */
 void phalcon_fast_strpos_str(zval *return_value, const zval *haystack, char *needle, unsigned int needle_length) {
 
+#if PHP_VERSION_ID >= 50600
+	const
+#endif
 	char *found = NULL;
 
 	if (unlikely(Z_TYPE_P(haystack) != IS_STRING)) {
@@ -441,6 +447,9 @@ void phalcon_fast_strpos_str(zval *return_value, const zval *haystack, char *nee
  */
 void phalcon_fast_stripos_str(zval *return_value, zval *haystack, char *needle, unsigned int needle_length) {
 
+#if PHP_VERSION_ID >= 50600
+	const
+#endif
 	char *found = NULL;
 	char *needle_dup, *haystack_dup;