diff --git a/basis/core-foundation/file-descriptors/file-descriptors.factor b/basis/core-foundation/file-descriptors/file-descriptors.factor
index bc982dff35..28b8b681f3 100644
--- a/basis/core-foundation/file-descriptors/file-descriptors.factor
+++ b/basis/core-foundation/file-descriptors/file-descriptors.factor
@@ -6,7 +6,13 @@ IN: core-foundation.file-descriptors
 
 TYPEDEF: void* CFFileDescriptorRef
 TYPEDEF: int CFFileDescriptorNativeDescriptor
-TYPEDEF: void* CFFileDescriptorCallBack
+
+CALLBACK: void CFFileDescriptorCallBack (
+   CFFileDescriptorRef f,
+   CFOptionFlags callBackTypes,
+   void *info
+) ;
+
 C-TYPE: CFFileDescriptorContext
 
 FUNCTION: CFFileDescriptorRef CFFileDescriptorCreate (
diff --git a/basis/core-foundation/run-loop/run-loop.factor b/basis/core-foundation/run-loop/run-loop.factor
index 14e80a5c98..724812d3c2 100644
--- a/basis/core-foundation/run-loop/run-loop.factor
+++ b/basis/core-foundation/run-loop/run-loop.factor
@@ -56,11 +56,6 @@ FUNCTION: void CFRunLoopRemoveTimer (
     CFStringRef mode
 ) ;
 
-CALLBACK: void CFRunLoopTimerCallBack (
-   CFRunLoopTimerRef timer,
-   void *info
-) ;
-
 CFSTRING: CFRunLoopDefaultMode "kCFRunLoopDefaultMode"
 
 TUPLE: run-loop-state fds sources timers ;
diff --git a/basis/core-foundation/timers/timers.factor b/basis/core-foundation/timers/timers.factor
index adf4e8a1c6..595b68df88 100644
--- a/basis/core-foundation/timers/timers.factor
+++ b/basis/core-foundation/timers/timers.factor
@@ -5,7 +5,12 @@ core-foundation.time calendar.unix kernel locals math system ;
 IN: core-foundation.timers
 
 TYPEDEF: void* CFRunLoopTimerRef
-TYPEDEF: void* CFRunLoopTimerCallBack
+
+CALLBACK: void CFRunLoopTimerCallBack (
+   CFRunLoopTimerRef timer,
+   void *info
+) ;
+
 TYPEDEF: void* CFRunLoopTimerContext
 
 FUNCTION: CFRunLoopTimerRef CFRunLoopTimerCreate (
diff --git a/basis/io/backend/unix/multiplexers/run-loop/run-loop.factor b/basis/io/backend/unix/multiplexers/run-loop/run-loop.factor
index 2bf03ec9a1..51405b203c 100644
--- a/basis/io/backend/unix/multiplexers/run-loop/run-loop.factor
+++ b/basis/io/backend/unix/multiplexers/run-loop/run-loop.factor
@@ -10,13 +10,12 @@ IN: io.backend.unix.multiplexers.run-loop
 TUPLE: run-loop-mx kqueue-mx ;
 
 : file-descriptor-callback ( -- callback )
-    void { CFFileDescriptorRef CFOptionFlags void* }
-    cdecl [
+    [
         3drop
         0 mx get-global kqueue-mx>> wait-for-events
         reset-run-loop
         yield
-    ] alien-callback ;
+    ] CFFileDescriptorCallBack ;
 
 : <run-loop-mx> ( -- mx )
     [