diff --git a/collects/tests/mzscheme/file.ss b/collects/tests/mzscheme/file.ss
index 70b0b78924..5904dd4150 100644
--- a/collects/tests/mzscheme/file.ss
+++ b/collects/tests/mzscheme/file.ss
@@ -952,7 +952,7 @@
 			 (semaphore-post lock))
 			(wrap-evt
 			 (semaphore-peek-evt lock)
-			 (lambda () 0)))))
+			 (lambda (v) 0)))))
 	     void)])
     (test-a-port p (gdelay go) gsync)))