1 files changed, 2 insertions, 0 deletions
diff --git a/regcomp.c b/regcomp.c
index 2283d109fa..7850492497 100644
--- a/regcomp.c
+++ b/regcomp.c
@@ -2168,6 +2168,8 @@ S_reg(pTHX_ RExC_state_t *pRExC_state, I32 paren, I32 *flagp)
 		/* FALL THROUGH*/
 	    case '?':           /* (??...) */
 		logical = 1;
+		if (*RExC_parse != '{')
+		    goto unknown;
 		paren = *RExC_parse++;
 		/* FALL THROUGH */
 	    case '{':           /* (?{...}) */