--- xz-5.1.1alpha/src/xz/hardware.c~	2011-04-12 12:42:58.000000000 +0200
+++ xz-5.1.1alpha/src/xz/hardware.c	2011-10-22 23:06:21.399474735 +0200
@@ -16,7 +16,7 @@
 
 /// Maximum number of worker threads. This can be set with
 /// the --threads=NUM command line option.
-static uint32_t threads_max = 1;
+static uint32_t threads_max = 0;
 
 /// Memory usage limit for compression
 static uint64_t memlimit_compress;
--- xz-5.1.1alpha/src/xz/xz.1~	2011-04-12 12:42:58.000000000 +0200
+++ xz-5.1.1alpha/src/xz/xz.1	2011-10-22 23:07:14.357449738 +0200
@@ -913,7 +913,7 @@
 .B 0
 makes
 .B xz
-use as many threads as there are CPU cores on the system.
+use as many threads as there are CPU cores on the system (default).
 The actual number of threads can be less than
 .I threads
 if the input file is not big enough