diff --git a/tgt-vvp/eval_real.c b/tgt-vvp/eval_real.c
index a61ab0f39..0c685624f 100644
--- a/tgt-vvp/eval_real.c
+++ b/tgt-vvp/eval_real.c
@@ -202,9 +202,9 @@ static void draw_realnum_real(ivl_expr_t expr)
 	    return;
       }
 
-      if (value < 0) {
+      if (signbit(value)) {
 	    sign = 0x4000;
-	    value *= -1;
+	    value = -value;
       }
 
       fract = frexp(value, &expo);