diff -Nurpd a/regparse.c b/regparse.c
--- a/regparse.c	2020-04-03 10:48:05.349134180 -0700
+++ b/regparse.c	2020-04-03 10:55:16.647309795 -0700
@@ -4412,9 +4412,11 @@ next_state_val(CClassNode* cc, OnigCodeP
 
   switch (*state) {
   case CCS_VALUE:
-    if (*type == CCV_SB)
+    if (*type == CCV_SB) {
+    	if (*from > 0xff)
+		return ONIGERR_INVALID_CODE_POINT_VALUE;
       BITSET_SET_BIT_CHKDUP(cc->bs, (int )(*vs));
-    else if (*type == CCV_CODE_POINT) {
+    } else if (*type == CCV_CODE_POINT) {
       r = add_code_range(&(cc->mbuf), env, *vs, *vs);
       if (r < 0) return r;
     }