diff --git a/lib/cpp/src/thrift/Thrift.h b/lib/cpp/src/thrift/Thrift.h
index 7b9a8ad..4d8d87c 100644
--- a/lib/cpp/src/thrift/Thrift.h
+++ b/lib/cpp/src/thrift/Thrift.h
@@ -86,6 +86,7 @@
   }
 
   bool operator !=(const TEnumIterator& end) {
+    (void)end;  // avoid "unused" warning with NDEBUG
     assert(end.n_ == -1);
     return (ii_ != n_);
   }