diff --git a/collects/drscheme/private/main.ss b/collects/drscheme/private/main.ss
index df7d8c5c8b..8aae53466e 100644
--- a/collects/drscheme/private/main.ss
+++ b/collects/drscheme/private/main.ss
@@ -247,23 +247,31 @@
 		(drscheme:unit:open-drscheme-window filename))])
 	 drscheme-current-create-new-window))
 
+      ;; add a catch-all handler to open drscheme files
+      (handler:insert-format-handler 
+       "Units"
+       (λ (filename) #t)
+       drscheme:unit:open-drscheme-window)
+      
       ;; add a handler to open .plt files.
       (handler:insert-format-handler 
        "PLT Files"
        (λ (filename)
-         (and (equal? "plt" (filename-extension filename))
-              (gui-utils:get-choice 
-               (format (string-constant install-plt-file) filename)
-               (string-constant install-plt-file/yes)
-               (string-constant install-plt-file/no))))
+         (let ([ext (filename-extension filename)])
+           (and ext
+                (or (bytes=? #"PLT" ext)
+                    (bytes=? #"plt" ext))
+                (gui-utils:get-choice 
+                 (format (string-constant install-plt-file) filename)
+                 (string-constant install-plt-file/yes)
+                 (string-constant install-plt-file/no)))))
        (λ (filename)
          (run-installer filename)
 	 #f))
       
       (drscheme:tools:load/invoke-all-tools
-       (λ ()
-         (void))
-       (λ ()
+       (λ () (void))
+       (λ () 
          (drscheme:language-configuration:add-built-in-languages)
          (drscheme:module-language:add-module-language)
          (drscheme:language-configuration:add-info-specified-languages)))
diff --git a/collects/drscheme/private/unit.ss b/collects/drscheme/private/unit.ss
index 6fb8e15279..4c5d37a8f5 100644
--- a/collects/drscheme/private/unit.ss
+++ b/collects/drscheme/private/unit.ss
@@ -3072,9 +3072,4 @@ module browser threading seems wrong.
                [frame (new drs-frame% (filename filename))])
           (send (send frame get-interactions-text) initialize-console)
           (send frame show #t)
-          frame))
-      
-      (handler:insert-format-handler 
-       "Units"
-       (λ (filename) #t)
-       open-drscheme-window))))
+          frame)))))
diff --git a/collects/framework/framework.ss b/collects/framework/framework.ss
index c042d5ac23..0d8b5c469f 100644
--- a/collects/framework/framework.ss
+++ b/collects/framework/framework.ss
@@ -722,7 +722,9 @@
     ". If \\var{pred} is a list of strings, they are each matched with the extension of a filename by"
     "@flink handler:find-format-handler %"
     ". If it is a function, the filename is applied to the function and the"
-    "functions result determines if this is the handler to use.")
+    "functions result determines if this is the handler to use."
+    ""
+    "The most recently added format handler takes precedence over all other format handlers.")
    (handler:find-named-format-handler
     (string? . -> . (path? . -> . (is-a?/c frame:editor<%>)))
     (name)