diff --git a/src/hb-ot-layout-common.hh b/src/hb-ot-layout-common.hh
index b07a40046..505a1e3ce 100644
--- a/src/hb-ot-layout-common.hh
+++ b/src/hb-ot-layout-common.hh
@@ -3122,6 +3122,8 @@ struct VarData
 
     regionIndices.len = new_ri_count;
 
+    if (unlikely (hb_unsigned_mul_overflows (get_row_size (), itemCount)))
+      return_trace (false);
     if (unlikely (!c->extend (this))) return_trace (false);
 
     for (r = 0; r < new_ri_count; r++)