diff --git a/lib/cpp/src/TReflectionLocal.h b/lib/cpp/src/TReflectionLocal.h
index 3fe7c63..8e39117 100644
--- a/lib/cpp/src/TReflectionLocal.h
+++ b/lib/cpp/src/TReflectionLocal.h
@@ -59,7 +59,7 @@
   }
 
   TypeSpec(TType ttype,
-           uint8_t* fingerprint,
+           const uint8_t* fingerprint,
            FieldMeta* metas,
            TypeSpec** specs) :
     ttype(ttype)