diff --git a/lib/midiator/drivers/core_midi.rb b/lib/midiator/drivers/core_midi.rb
index 2bd4117..fd0a65b 100644
--- a/lib/midiator/drivers/core_midi.rb
+++ b/lib/midiator/drivers/core_midi.rb
@@ -22,6 +22,10 @@
 require 'midiator/driver_registry'
 
 class MIDIator::Driver::CoreMIDI < MIDIator::Driver # :nodoc:
+
+  # Figure out if we have SnowLeopard
+  SNOW_LEOPARD = `uname -r` =~ /10\.\d\.\d/
+
   ##########################################################################
   ### S Y S T E M   I N T E R F A C E
   ##########################################################################
@@ -35,7 +39,11 @@ module C # :nodoc:
     extern "void* MIDIGetDestination( int )"
     extern "int MIDIOutputPortCreate( void*, void*, void* )"
     extern "void* MIDIPacketListInit( void* )"
-    extern "void* MIDIPacketListAdd( void*, int, void*, int, int, int, void* )"
+    if SNOW_LEOPARD
+      extern "void* MIDIPacketListAdd( void*, int, void*, int, int, void* )"
+    else
+      extern "void* MIDIPacketListAdd( void*, int, void*, int, int, int, void* )"
+    end
     extern "int MIDISend( void*, void*, void* )"
   end
 
@@ -75,7 +83,11 @@ def message( *args )
     packet_ptr = C.mIDIPacketListInit( packet_list )
 
     # Pass in two 32-bit 0s for the 64 bit time
-    packet_ptr = C.mIDIPacketListAdd( packet_list, 256, packet_ptr, 0, 0, args.size, bytes )
+    if SNOW_LEOPARD
+      packet_ptr = C.mIDIPacketListAdd( packet_list, 256, packet_ptr, 0, args.size, bytes )
+    else
+      packet_ptr = C.mIDIPacketListAdd( packet_list, 256, packet_ptr, 0, 0, args.size, bytes )
+    end
 
     C.mIDISend( @outport, @destination, packet_list )
   end