diff --git a/arch/um/drivers/mconsole_kern.c b/arch/um/drivers/mconsole_kern.c
index 18d0ec15557c..f01b7d8a07bc 100644
--- a/arch/um/drivers/mconsole_kern.c
+++ b/arch/um/drivers/mconsole_kern.c
@@ -117,10 +117,12 @@ void mconsole_log(struct mc_request *req)
 	int len;
 	char *ptr = req->request.data;
 
-	ptr += strlen("log ");
+	ptr += strlen(req->cmd->command);
+	ptr = skip_spaces(ptr);
 
-	len = req->len - (ptr - req->request.data);
-	printk(KERN_WARNING "%.*s", len, ptr);
+	len = req->request.len - (ptr - req->request.data);
+	if (len > 0)
+		printk(KERN_WARNING "%.*s", len, ptr);
 	mconsole_reply(req, "", 0, 0);
 }