diff --git a/src/backend/regex/regexec.c b/src/backend/regex/regexec.c
index 34381ff8d9..460c987a60 100644
--- a/src/backend/regex/regexec.c
+++ b/src/backend/regex/regexec.c
@@ -196,6 +196,8 @@ pg_regexec(regex_t *re,
 		return REG_INVARG;
 	if (re->re_csize != sizeof(chr))
 		return REG_MIXED;
+	if (search_start > len)
+		return REG_NOMATCH;
 
 	/* Initialize locale-dependent support */
 	pg_set_regex_collation(re->re_collation);