diff --git a/ext/standard/string.c b/ext/standard/string.c
index faca6fd0f90..fe0ae0a039d 100644
--- a/ext/standard/string.c
+++ b/ext/standard/string.c
@@ -1588,7 +1588,7 @@ PHP_FUNCTION(chunk_split)
 	convert_to_string_ex(p_str);
 
 	if (argc > 1) {
-		convert_to_string_ex(p_chunklen);
+		convert_to_long_ex(p_chunklen);
 		chunklen = Z_LVAL_PP(p_chunklen);
 	}