diff --git a/src/typval.c b/src/typval.c
index c859122..fb945cb 100644
--- a/src/typval.c
+++ b/src/typval.c
@@ -1822,7 +1822,8 @@
 		      : STR2NR_ALL, &n, NULL, 0, TRUE);
 	if (len == 0)
 	{
-	    semsg(_(e_invalid_expression_str), *arg);
+	    if (evaluate)
+		semsg(_(e_invalid_expression_str), *arg);
 	    return FAIL;
 	}
 	*arg += len;