diff --git a/collects/mzlib/date.rkt b/collects/mzlib/date.rkt
index 8e78a0c..13ec0e0 100644
--- a/collects/mzlib/date.rkt
+++ b/collects/mzlib/date.rkt
@@ -289,7 +289,7 @@
                             (if (<= input test)
                                 'input-smaller
                                 'test-smaller)))]))])
-      ; (printf "~a ~a ~a~n" compare secs (date->string date))
+      ; (printf "~a ~a ~a\n" compare secs (date->string date))
       (cond
         [(eq? compare 'equal) secs]
         [(or (= secs below-secs) (= secs above-secs))
@@ -362,4 +362,4 @@
                                              (caddr reversed-digits)
                                              (cadr reversed-digits)
                                              (car reversed-digits)))
-                                (loop (cdr (cdr (cdr reversed-digits))))))))))))
\ No newline at end of file
+                                (loop (cdr (cdr (cdr reversed-digits))))))))))))
diff --git a/collects/mzlib/integer-set.rkt b/collects/mzlib/integer-set.rkt
index ac7bcce..10e8b69 100644
--- a/collects/mzlib/integer-set.rkt
+++ b/collects/mzlib/integer-set.rkt
@@ -8,7 +8,7 @@
        (let* defs
          (let ((real-ans code))
            (unless (equal? real-ans right-ans)
-             (printf "Test failed: ~e gave ~e.  Expected ~e~n"
+             (printf "Test failed: ~e gave ~e.  Expected ~e\n"
                      'code real-ans 'right-ans))) ...))))
 
   (define-syntax test-block
diff --git a/collects/mzlib/thread.rkt b/collects/mzlib/thread.rkt
index 5ce3aa4..4c4d005 100644
--- a/collects/mzlib/thread.rkt
+++ b/collects/mzlib/thread.rkt
@@ -115,7 +115,7 @@
 
   ;; coroutine : ((bool ->) -> X) -> X-coroutine-object
   (define (coroutine f)
-    ;;(printf "2. new coroutine~n")
+    ;;(printf "2. new coroutine\n")
     (let* ([can-stop-lock (make-semaphore 1)]
            [done-ch (make-channel)]
            [ex-ch (make-channel)]
@@ -123,7 +123,7 @@
            [stop-enabled? #t]
            [enable-stop
             (lambda (enable?)
-              ;;(printf "3. enabling ~a~n" enable?)
+              ;;(printf "3. enabling ~a\n" enable?)
               (cond
                [(and enable? (not stop-enabled?))
                 (semaphore-post can-stop-lock)
@@ -131,11 +131,11 @@
                [(and (not enable?) stop-enabled?)
                 (semaphore-wait can-stop-lock)
                 (set! stop-enabled? #f)])
-              ;;(printf "3. finished enabling~n")
+              ;;(printf "3. finished enabling\n")
               )]
            [tid (thread (lambda ()
                           (semaphore-wait proceed-sema)
-                          ;;(printf "3. creating coroutine thread~n")
+                          ;;(printf "3. creating coroutine thread\n")
                           (with-handlers ([(lambda (exn) #t)
                                            (lambda (exn)
                                              (enable-stop #t)
@@ -152,7 +152,7 @@
     (if (coroutine-object-worker w)
       (let ([can-stop-lock (coroutine-object-can-stop-lock w)]
             [worker (coroutine-object-worker w)])
-        #;(printf "2. starting coroutine~n")
+        #;(printf "2. starting coroutine\n")
         (thread-resume worker)
         (dynamic-wind
           void
@@ -162,20 +162,20 @@
                                             timeout
                                             (alarm-evt (+ timeout (current-inexact-milliseconds))))
                                         (lambda (x)
-                                          #;(printf "2. alarm-evt~n")
+                                          #;(printf "2. alarm-evt\n")
                                           (semaphore-wait can-stop-lock)
                                           (thread-suspend worker)
                                           (semaphore-post can-stop-lock)
                                           #f))
                               (wrap-evt (coroutine-object-done-ch w)
                                         (lambda (res)
-                                          #;(printf "2. coroutine-done-evt~n")
+                                          #;(printf "2. coroutine-done-evt\n")
                                           (set-coroutine-object-result! w res)
                                           (coroutine-kill w)
                                           #t))
                               (wrap-evt (coroutine-object-ex-ch w)
                                         (lambda (exn)
-                                          #;(printf "2. ex-evt~n")
+                                          #;(printf "2. ex-evt\n")
                                           (coroutine-kill w)
                                           (raise exn))))))
           ;; In case we escape through a break:
diff --git a/collects/mzlib/traceld.rkt b/collects/mzlib/traceld.rkt
index f4a3f20..4d929fa 100644
--- a/collects/mzlib/traceld.rkt
+++ b/collects/mzlib/traceld.rkt
@@ -8,7 +8,7 @@
          (lambda (load)
            (lambda (filename expected-module)
              (fprintf ep
-                      "~aloading ~a at ~a~n" 
+                      "~aloading ~a at ~a\n" 
                       tab filename (current-process-milliseconds))
              (begin0
               (let ([s tab])
@@ -18,7 +18,7 @@
                       (load filename expected-module))
                     (lambda () (set! tab s))))
               (fprintf ep
-                       "~adone ~a at ~a~n"
+                       "~adone ~a at ~a\n"
                        tab filename (current-process-milliseconds)))))])
     (current-load (mk-chain load))
     (current-load-extension (mk-chain load-extension))))
diff --git a/collects/tests/racket/macrolib.rktl b/collects/tests/racket/macrolib.rktl
index 23eb8b0..2f1ab25 100644
--- a/collects/tests/racket/macrolib.rktl
+++ b/collects/tests/racket/macrolib.rktl
@@ -97,7 +97,7 @@
 (define (opt-lam-test exp expected)
    (let ([got (eval exp)])
      (unless (equal? got expected)
-       (printf  "FAILED test: ~a~n   expected: ~s~n        got: ~s~n"
+       (printf  "FAILED test: ~a\n   expected: ~s\n        got: ~s\n"
                 exp expected got))))
 
 (define (opt-lam-test/bad exp expected)
@@ -105,7 +105,7 @@
                                (lambda (exn) (exn-message exn))])
                 (cons 'got-result (eval exp)))])
      (unless (regexp-match expected got)
-       (printf  "FAILED test: ~a~n   expected: ~s~n        got: ~s~n"
+       (printf  "FAILED test: ~a\n   expected: ~s\n        got: ~s\n"
                 exp expected got))))
 
 (test 1 (opt-lambda (start) start) 1)
diff --git a/collects/tests/racket/pconvert.rktl b/collects/tests/racket/pconvert.rktl
index 534ec11..484ee47 100644
--- a/collects/tests/racket/pconvert.rktl
+++ b/collects/tests/racket/pconvert.rktl
@@ -51,11 +51,11 @@
                                        [whole/fractional-exact-numbers whole/fractional-numbers?])
                           (test (selector test-case) print-convert before))
                   (printf
-                   ">> (constructor-style-printing ~a) (quasi-read-style-printing ~a) (show-sharing ~a) (abbreviate-cons-as-list ~a) (whole/fractional-exact-numbers ~a)~n"
+                   ">> (constructor-style-printing ~a) (quasi-read-style-printing ~a) (show-sharing ~a) (abbreviate-cons-as-list ~a) (whole/fractional-exact-numbers ~a)\n"
                    constructor-style? quasi-read? 
                    sharing? cons-as-list?
                    whole/fractional-numbers?)))])
-        ;(printf "testing: ~s~n" before)
+        ;(printf "testing: ~s\n" before)
         ;(printf ".") (flush-output (current-output-port))
         (cond
           [(pctest? test-case)