diff --git a/Announce b/Announce
index ea51a70d8a..195594c146 100755
--- a/Announce
+++ b/Announce
@@ -1,7 +1,7 @@
 #!/bin/sh
 # Announcement message skelton
 #
-MASTER=master
+: ${MASTER=master}
 
 tmpbase=/var/tmp/git-announce.$$
 trap 'rm -f $tmpbase.*' 0