diff --git a/basis/core-foundation/timers/tags.txt b/basis/core-foundation/timers/tags.txt
new file mode 100644
index 0000000000..2320bdd648
--- /dev/null
+++ b/basis/core-foundation/timers/tags.txt
@@ -0,0 +1,2 @@
+unportable
+bindings
diff --git a/basis/core-foundation/timers/timers.factor b/basis/core-foundation/timers/timers.factor
index 1d17d99a4d..049e80b20f 100644
--- a/basis/core-foundation/timers/timers.factor
+++ b/basis/core-foundation/timers/timers.factor
@@ -1,6 +1,6 @@
 ! Copyright (C) 2008 Slava Pestov.
 ! See http://factorcode.org/license.txt for BSD license.
-USING: alien.syntax system math kernel ;
+USING: alien.syntax system math kernel core-foundation ;
 IN: core-foundation.timers
 
 TYPEDEF: void* CFRunLoopTimerRef