diff --git a/dtl/Diff.hpp b/dtl/Diff.hpp
index 8c9c774f..57067f9f 100644
--- a/dtl/Diff.hpp
+++ b/dtl/Diff.hpp
@@ -164,7 +164,7 @@ namespace dtl {
             return trivial;
         }
         
-        void enableTrivial () const {
+        void enableTrivial () {
             this->trivial = true;
         }