diff --git a/collects/macro-debugger/model/deriv-parser.rkt b/collects/macro-debugger/model/deriv-parser.rkt
index 1290e47..8b1325b 100644
--- a/collects/macro-debugger/model/deriv-parser.rkt
+++ b/collects/macro-debugger/model/deriv-parser.rkt
@@ -164,9 +164,7 @@
      [(enter-prim (? Prim) exit-prim return)
       (begin
         (unless (eq? $3 $4)
-          (fprintf (current-error-port)
-                   "warning: exit-prim and return differ:\n~s\n~s\n"
-                   $3 $4))
+          (eprintf "warning: exit-prim and return differ:\n~s\n~s\n" $3 $4))
         ($2 $1 $3 rs))]
      [((? MacroStep) (? EE))
       ($1 e1 rs $2)])
diff --git a/collects/macro-debugger/model/reductions-config.rkt b/collects/macro-debugger/model/reductions-config.rkt
index 599ff05..e6ab4fb 100644
--- a/collects/macro-debugger/model/reductions-config.rkt
+++ b/collects/macro-debugger/model/reductions-config.rkt
@@ -285,12 +285,10 @@
            ;; But for now, just drop it to avoid macro stepper error.
            ;; Only bad effect should be missed subterms (usually at phase1).
            (STRICT-CHECKS
-            (fprintf (current-error-port)
-                     "from:\n~.s\n\nto:\n~.s\n\n"
+            (eprintf "from:\n~.s\n\nto:\n~.s\n\n"
                      (stx->datum from)
                      (stx->datum to))
-            (fprintf (current-error-port)
-                     "original from:\n~.s\n\noriginal to:\n~.s\n\n"
+            (eprintf "original from:\n~.s\n\noriginal to:\n~.s\n\n"
                      (stx->datum from0)
                      (stx->datum to0))
             (error 'add-to-renames-table))
diff --git a/collects/macro-debugger/model/reductions-engine.rkt b/collects/macro-debugger/model/reductions-engine.rkt
index 7f43d2b..7e9ea22 100644
--- a/collects/macro-debugger/model/reductions-engine.rkt
+++ b/collects/macro-debugger/model/reductions-engine.rkt
@@ -540,17 +540,13 @@
            [expected-datum (stx->datum expected)]
            [same-form? (equal? actual-datum expected-datum)])
       (if same-form?
-          (fprintf (current-error-port)
-                   "same form but wrong wrappings:\n~.s\nwrongness:\n~.s\n"
+          (eprintf "same form but wrong wrappings:\n~.s\nwrongness:\n~.s\n"
                    actual-datum
                    (wrongness actual expected))
-          (fprintf (current-error-port)
-                   "got:\n~.s\n\nexpected:\n~.s\n"
+          (eprintf "got:\n~.s\n\nexpected:\n~.s\n"
                    actual-datum
                    expected-datum))
-      (for ([d derivs])
-        (fprintf (current-error-port)
-                 "\n~.s\n" d))
+      (for ([d derivs]) (eprintf "\n~.s\n" d))
       (error function
              (if same-form?
                  "wrong starting point (wraps)!"
diff --git a/collects/macro-debugger/model/reductions.rkt b/collects/macro-debugger/model/reductions.rkt
index c7b9241..0f54430 100644
--- a/collects/macro-debugger/model/reductions.rkt
+++ b/collects/macro-debugger/model/reductions.rkt
@@ -760,7 +760,7 @@
 
 ;; lift-error
 (define (lift-error sym . args)
-  (apply fprintf (current-error-port) args)
+  (apply eprintf args)
   (newline (current-error-port))
   (when #f
     (apply error sym args)))