--- tools/versioncheck
+++ tools/versioncheck
@@ -1,7 +1,7 @@
 #!/bin/sh
 SCCP_BRANCH="unknown"
 SCCP_VERSION="unknown"
-SCCP_REVISION="unknown"
+SCCP_REVISION="${SCCP_REVISION:-unknown}"
 
 if test -d .svn || test -d ../.svn || test -d ../../.svn;then
   if test ! -z "`which svn`"; then
--- autoconf/acinclude.m4
+++ autoconf/acinclude.m4
@@ -333,7 +333,7 @@
 #  AC_UNDEFINE("PACKAGE_VERSION")
   SCCP_BRANCH="unknown"
   SCCP_VERSION="unknown"
-  SCCP_REVISION="unknown"
+  SCCP_REVISION="${SCCP_REVISION:-unknown}"
 
   BASE=`dirname $ac_dir`
   pushd $BASE >/dev/null