--- /n/sources/plan9/sys/src/cmd/gzip/unzip.c	Fri Feb 28 10:50:04 2014
+++ /sys/src/cmd/gzip/unzip.c	Thu Oct 10 07:42:13 2013
@@ -652,6 +652,8 @@ trailer(Biobuf *bin, ZipHead *zh)
 {
 	if(zh->flags & ZTrailInfo){
 		zh->crc = get4(bin);
+		if(zh->crc == ZTHeader)
+			zh->crc = get4(bin);
 		zh->csize = get4(bin);
 		zh->uncsize = get4(bin);
 	}
--- /n/sources/plan9/sys/src/cmd/gzip/zip.h	Wed Jun  7 17:23:05 2000
+++ /sys/src/cmd/gzip/zip.h	Thu Oct 10 07:42:13 2013
@@ -8,6 +8,7 @@ enum
 	ZHeader		= 0x04034b50,
 	ZCHeader	= 0x02014b50,
 	ZECHeader	= 0x06054b50,
+	ZTHeader	= 0x08074b50,	/* optional trailer signature */
 
 	/*
 	 * "general purpose flag" bits
--- /n/sources/plan9/sys/src/cmd/tapefs/zip.h	Sun Oct 17 06:00:10 2004
+++ /sys/src/cmd/tapefs/zip.h	Thu Oct 10 07:42:13 2013
@@ -8,6 +8,7 @@ enum
 	ZHeader		= 0x04034b50,
 	ZCHeader	= 0x02014b50,
 	ZECHeader	= 0x06054b50,
+	ZTHeader	= 0x08074b50,	/* optional trailer signature */
 
 	/*
 	 * "general purpose flag" bits
--- /n/sources/plan9/sys/src/cmd/tapefs/zipfs.c	Sat Feb 25 06:00:05 2006
+++ /sys/src/cmd/tapefs/zipfs.c	Thu Oct 10 07:42:13 2013
@@ -300,6 +300,8 @@ trailer(Biobuf *bin, ZipHead *zh)
 {
 	if(zh->flags & ZTrailInfo){
 		zh->crc = get4(bin);
+		if(zh->crc == ZTHeader)
+			zh->crc = get4(bin);
 		zh->csize = get4(bin);
 		zh->uncsize = get4(bin);
 	}