--- a/src/rail.h	Wed Jun 27 01:01:16 2007 +0000
+++ b/src/rail.h	Sat Jul 07 09:20:52 2007 +0000
@@ -290,8 +290,8 @@
 */
 static inline Track TrackBitsToTrack(TrackBits tracks)
 {
-	assert(tracks == INVALID_TRACK_BIT || (tracks != TRACK_BIT_NONE && KILL_FIRST_BIT(tracks) == 0));
-	return tracks != INVALID_TRACK_BIT ? (Track)FIND_FIRST_BIT(tracks) : INVALID_TRACK;
+	assert(tracks == INVALID_TRACK_BIT || (tracks != TRACK_BIT_NONE && KILL_FIRST_BIT(tracks & TRACK_BIT_MASK) == 0));
+	return tracks != INVALID_TRACK_BIT ? (Track)FIND_FIRST_BIT(tracks & TRACK_BIT_MASK) : INVALID_TRACK;
 }
 
 /**