diff --git a/tools/cmp-cvs.sh b/tools/cmp-cvs.sh
new file mode 100644
index 00000000..da99a017
--- /dev/null
+++ b/tools/cmp-cvs.sh
@@ -0,0 +1,5 @@
+# $Id: cmp-cvs.sh,v 1.1 2009-06-25 16:49:22 nicm Exp $
+
+for i in *.[ch]; do
+    diff -u $i /usr/src/usr.bin/tmux/$i
+done