--- xnu/xnu-792.25.20/iokit/Kernel/IOEventSource.cpp
+++ xnu/xnu-344.32/iokit/Kernel/IOEventSource.cpp
@@ -54,7 +54,7 @@
         { workLoop->wakeupGate(event, oneThread); }
 
 bool IOEventSource::init(OSObject *inOwner,
-                         Action inAction)
+                         Action inAction = 0)
 {
     if (!inOwner)
         return false;