diff --git a/basis/concurrency/mailboxes/debugger/authors.txt b/basis/concurrency/mailboxes/debugger/authors.txt
new file mode 100755
index 0000000000..56f4654064
--- /dev/null
+++ b/basis/concurrency/mailboxes/debugger/authors.txt
@@ -0,0 +1 @@
+Slava Pestov
diff --git a/basis/concurrency/mailboxes/debugger/debugger.factor b/basis/concurrency/mailboxes/debugger/debugger.factor
new file mode 100755
index 0000000000..c222ab0a16
--- /dev/null
+++ b/basis/concurrency/mailboxes/debugger/debugger.factor
@@ -0,0 +1,8 @@
+! Copyright (C) 2010 Slava Pestov.
+! See http://factorcode.org/license.txt for BSD license.
+USING: debugger accessors debugger.threads kernel
+concurrency.mailboxes ;
+IN: concurrency.mailboxes.debugger
+
+M: linked-error error.
+    [ thread>> error-in-thread. ] [ error>> error. ] bi ;
diff --git a/basis/concurrency/mailboxes/mailboxes.factor b/basis/concurrency/mailboxes/mailboxes.factor
old mode 100644
new mode 100755
index 163873575c..df73c36183
--- a/basis/concurrency/mailboxes/mailboxes.factor
+++ b/basis/concurrency/mailboxes/mailboxes.factor
@@ -2,8 +2,7 @@
 ! See http://factorcode.org/license.txt for BSD license.
 USING: dlists deques threads sequences continuations namespaces
 math quotations words kernel arrays assocs init system
-concurrency.conditions accessors debugger debugger.threads
-locals fry ;
+concurrency.conditions accessors locals fry vocabs.loader ;
 IN: concurrency.mailboxes
 
 TUPLE: mailbox { threads dlist } { data dlist } ;
@@ -77,9 +76,6 @@ M: mailbox mailbox-get-timeout block-if-empty data>> pop-back ;
 
 TUPLE: linked-error error thread ;
 
-M: linked-error error.
-    [ thread>> error-in-thread. ] [ error>> error. ] bi ;
-
 C: <linked-error> linked-error
 
 : ?linked ( message -- message )
@@ -95,3 +91,5 @@ M: linked-thread error-in-thread
 
 : spawn-linked-to ( quot name mailbox -- thread )
     <linked-thread> [ (spawn) ] keep ;
+
+{ "concurrency.mailboxes" "debugger" } "concurrency.mailboxes.debugger" require-when