diff --git a/tgt-vvp/eval_expr.c b/tgt-vvp/eval_expr.c
index bca49cc0a..f7c5ed27d 100644
--- a/tgt-vvp/eval_expr.c
+++ b/tgt-vvp/eval_expr.c
@@ -1246,7 +1246,7 @@ static struct vector_info draw_binary_expr_arith(ivl_expr_t exp, unsigned wid)
       struct vector_info lv;
       struct vector_info rv;
 
-      const char*sign_string = ivl_expr_signed(exp)? "/s" : "";
+      const char*sign_string = ivl_expr_signed(le) && ivl_expr_signed(re)? "/s" : "";
 
       if ((ivl_expr_opcode(exp) == '+')
 	  && (ivl_expr_type(le) == IVL_EX_SIGNAL)