diff --git a/pkgs/gui-pkgs/gui-lib/framework/preferences.rkt b/pkgs/gui-pkgs/gui-lib/framework/preferences.rkt
index c713ce30..aa81ec9d 100644
--- a/pkgs/gui-pkgs/gui-lib/framework/preferences.rkt
+++ b/pkgs/gui-pkgs/gui-lib/framework/preferences.rkt
@@ -144,7 +144,7 @@ the state transitions / contracts are:
              (error 'preferences:set
                     (string-append
                      "new value doesn't satisfy preferences:set-default predicate\n"
-                     "  pref sym: ~e\n"
+                     "  pref sym: ~v\n"
                      "  given: ~e\n"
                      "  predicate: ~e")
                      p value checker?))
diff --git a/pkgs/gui-pkgs/gui-lib/framework/private/editor.rkt b/pkgs/gui-pkgs/gui-lib/framework/private/editor.rkt
index 0862811c..dc493725 100644
--- a/pkgs/gui-pkgs/gui-lib/framework/private/editor.rkt
+++ b/pkgs/gui-pkgs/gui-lib/framework/private/editor.rkt
@@ -456,7 +456,8 @@
        (get-current-preferred-font-size))))
   
   
-  (define (set-current-preferred-font-size new-size)
+  (define/contract (set-current-preferred-font-size new-size)
+    (-> exact-nonnegative-integer? void?)
     (define old-pref (preferences:get 'framework:standard-style-list:font-size))
     (define current-mons (get-current-monitor-sizes))
     (define new-monitor-sizes