diff --git a/src/hb-ot-cff-common.hh b/src/hb-ot-cff-common.hh
index 5ec1361a8..a83435d49 100644
--- a/src/hb-ot-cff-common.hh
+++ b/src/hb-ot-cff-common.hh
@@ -233,7 +233,7 @@ struct CFFIndex
   inline unsigned int max_offset (void) const
   {
     unsigned int max = 0;
-    for (unsigned int i = 0; i <= count; i++)
+    for (unsigned int i = 0; i < count + 1; i++)
     {
       unsigned int off = offset_at (i);
       if (off > max) max = off;