diff --git a/collects/drracket/private/auto-language.rkt b/collects/drracket/private/auto-language.rkt
index 1b1c4c3081..97691ac3b2 100644
--- a/collects/drracket/private/auto-language.rkt
+++ b/collects/drracket/private/auto-language.rkt
@@ -80,4 +80,4 @@
                ;; If tp contains a snip, read-line fails.
                (read-line tp))])
     (and (string? l1)
-         (regexp-match? #rx"#lang .*$" (assert l1 string?)))))
+         (regexp-match? #rx"#lang .*$" l1))))