diff --git a/eval_tree.cc b/eval_tree.cc
index deb313f34..3f278f842 100644
--- a/eval_tree.cc
+++ b/eval_tree.cc
@@ -1703,6 +1703,7 @@ NetExpr* evaluate_clog2(NetExpr*&arg_)
 		  res = integer_width;
 
 	    verinum tmp (res, integer_width);
+	    tmp.has_sign(true);
 	    NetEConst*rtn = new NetEConst(tmp);
 	    return rtn;
       }