diff --git a/src/filepath.c b/src/filepath.c
index 79eb7bf..49b814f 100644
--- a/src/filepath.c
+++ b/src/filepath.c
@@ -1929,7 +1929,8 @@
     }
     else
     {
-	semsg(_(e_invarg2), "writefile()");
+	semsg(_(e_invarg2),
+		_("writefile() first argument must be a List or a Blob"));
 	return;
     }