diff --git a/src/hb-set.hh b/src/hb-set.hh
index b6e2086a2..81cd2b524 100644
--- a/src/hb-set.hh
+++ b/src/hb-set.hh
@@ -544,6 +544,7 @@ struct hb_set_t
   void process (const Op& op, const hb_set_t *other)
   {
     if (unlikely (!successful)) return;
+    if (unlikely (!other->successful)) return;
 
     dirty ();
 
diff --git a/test/fuzzing/fonts/clusterfuzz-testcase-minimized-hb-subset-fuzzer-5345734743031808 b/test/fuzzing/fonts/clusterfuzz-testcase-minimized-hb-subset-fuzzer-5345734743031808
new file mode 100644
index 000000000..193cf8958
Binary files /dev/null and b/test/fuzzing/fonts/clusterfuzz-testcase-minimized-hb-subset-fuzzer-5345734743031808 differ