diff --git a/collects/plai/scribblings/plai.scrbl b/collects/plai/scribblings/plai.scrbl
index 7606d65053..54fdc83bcf 100644
--- a/collects/plai/scribblings/plai.scrbl
+++ b/collects/plai/scribblings/plai.scrbl
@@ -124,7 +124,8 @@ PLAI Scheme provides the following syntactic forms for testing.
 @defform/subs[(test result-expr expected-expr)()]{
 
 If @racket[_result-expr] and @racket[_expected-expr] evaluate to the same
-value, @racket[_result-value], the test prints
+value, @racket[_result-value], the test prints the following expression
+to @racket[(current-error-port)]:
 
 @racketresultfont{(good result-expr result-value expected-value location)}.
 
diff --git a/collects/plai/test-harness.rkt b/collects/plai/test-harness.rkt
index a3f9575331..0d46dc471e 100644
--- a/collects/plai/test-harness.rkt
+++ b/collects/plai/test-harness.rkt
@@ -69,9 +69,8 @@
     (set! plai-all-test-results (cons result plai-all-test-results))
     (when print?
       (if (abridged-test-output)
-          (apply printf "(~s ~v ~v)" result)
-          (apply printf "(~s ~s ~v ~v ~s)" result))
-      (newline))
+          (apply eprintf "(~s ~v ~v)\n" result)
+          (apply eprintf "(~s ~s ~v ~v ~s)\n" result)))
     (when (and halt-on-errors? error?)
       (raise (make-exn:test (string->immutable-string (format "test failed: ~s" result))
                             (current-continuation-marks))))))
diff --git a/collects/tests/plai/test-harness.rkt b/collects/tests/plai/test-harness.rkt
index fc5ad2fc49..49ba469043 100644
--- a/collects/tests/plai/test-harness.rkt
+++ b/collects/tests/plai/test-harness.rkt
@@ -7,7 +7,13 @@
   [id (s symbol?)])
 
 (define-syntax-rule (->string e)
-  (regexp-replace "line [0-9]+" (with-output-to-string (λ () e)) "line ??"))
+  (regexp-replace "line [0-9]+" (with-err-output-to-string (λ () e)) "line ??"))
+
+(define (with-err-output-to-string thunk)
+  (define sp (open-output-string))
+  (parameterize ([current-error-port sp])
+    (thunk))
+  (get-output-string sp))
 
 (define (go catch? errors? abridged?)
   (eli:test