diff --git a/tests/error.rkt b/tests/error.rkt
index d84b607..d06891e 100644
--- a/tests/error.rkt
+++ b/tests/error.rkt
@@ -6,11 +6,14 @@
 (test-begin
  (after
   (define (do-test files)
-    (apply test-files! files)
+    (define o (open-output-string))
+    (parameterize ([current-error-port o])
+      (apply test-files! files))
+    (define s (get-output-string o))
     (define c (get-test-coverage))
     (define covered (hash-keys c))
     (for-each
-     (lambda (x) (check-not-false (member x covered)))
+     (lambda (x) (check-not-false (member x covered) s))
      files)
     (clear-coverage!))
   (define files (map path->string (list error main)))