diff --git a/lib/idn.c b/lib/idn.c
index 475d9c9beb..a024691d1f 100644
--- a/lib/idn.c
+++ b/lib/idn.c
@@ -91,6 +91,8 @@ static CURLcode win32_idn_to_ascii(const char *in, char **out)
     else
       return CURLE_URL_MALFORMAT;
   }
+  else
+    return CURLE_URL_MALFORMAT;
 
   return CURLE_OK;
 }