diff --git a/ext/json/json_parser.y b/ext/json/json_parser.y
index 72f2890f6f1..75c8ffb4a8c 100644
--- a/ext/json/json_parser.y
+++ b/ext/json/json_parser.y
@@ -158,7 +158,7 @@ errlex:
 	
 %% /* Functions */
 
-void php_json_parser_init(php_json_parser *parser, zval *return_value, char *str, int str_len, long options, long max_depth)
+void php_json_parser_init(php_json_parser *parser, zval *return_value, char *str, size_t str_len, long options, long max_depth)
 {
 	memset(parser, 0, sizeof(php_json_parser));
 	php_json_scanner_init(&parser->scanner, str, str_len, options);
diff --git a/ext/json/php_json_parser.h b/ext/json/php_json_parser.h
index ec20950aa33..cc43d44e9d6 100644
--- a/ext/json/php_json_parser.h
+++ b/ext/json/php_json_parser.h
@@ -29,7 +29,7 @@ typedef struct _php_json_parser {
 	long max_depth;
 } php_json_parser;
 
-void php_json_parser_init(php_json_parser *parser, zval *return_value, char *str, int str_len, long options, long max_depth);
+void php_json_parser_init(php_json_parser *parser, zval *return_value, char *str, size_t str_len, long options, long max_depth);
 
 php_json_error_code php_json_parser_error_code(php_json_parser *parser);