diff --git a/mksnap.sh b/mksnap.sh
index b5e9aeeecd80367b602120afefd1738200eecc81..8a0612c3da7d002d34398629f22580f74831c153 100755
--- a/mksnap.sh
+++ b/mksnap.sh
@@ -20,22 +20,48 @@ if test -z "${SSH_AGENT_PID}" -o -z "${SSH_AUTH_SOCK}"; then
     exit 1
 fi
 
-trap "chmod -$ u+rwX ${MYTMPDIR} ; rm -rf ${MYTMPDIR}" 0
+trap "chmod -R u+rwX ${MYTMPDIR} ; rm -rf ${MYTMPDIR}" 0
+
 mkdir -p "${MYTMPDIR}"
 cd "${MYTMPDIR}"
 svn co ${SVNREPOS}/${ALBERTADIST} albertadist
 cd albertadist
+# own revision
+HEADREV=`svn info|grep "Last Changed Rev" |awk '{ print $4; }'`
+LASTREV=`{ ls -C1 --color=no ${SNAPSHOTDIR}/*.gz || true; }|tail -n 1|cut -d '-' -f 3|cut -d '.' -f 1`
+if test -n "${LASTREV}"; then
+    # figure out if anything has changed.
+    for i in . alberta alberta_util demo add_ons doc; do
+	(
+	    cd $i
+	    svn diff -r ${LASTREV} > ${MYTMPDIR}/svn.diff
+	    if test -s ${MYTMPDIR}/svn.diff; then
+		CHANGED=true
+	    fi
+	)
+	if test "z${CHANGED}" = ztrue; then
+	    break;
+	fi
+    done
+    if ! test "z${CHANGED}" = ztrue; then
+	# nothing changed, do not prepare a new snapshot
+	exit 0
+    fi
+fi
 #
 # attach the time-stamp to the package
 #
-sed -i -e 's/AC_INIT([alberta2],[^,]\+,/AC_INIT([alberta2],['"${DATE}"'],/g' configure.ac
+VERSTAMP="${DATE}-${HEADREV}"
+sed -i -e 's/AC_INIT(\[alberta2\], [^,]\+,/AC_INIT([alberta2], ['"${VERSTAMP}"'],/g' configure.ac
 ./fromsvnreconf.sh
-./configure
+./configure --enable-maintainer-mode
 make distcheck
 
-if test -f "alberta2-${DATE}.tar.bz2" -a -f "alberta2-${DATE}.tar.gz"; then
+if test -f "alberta2-${VERSTAMP}.tar.bz2" -a \
+        -f "alberta2-${VERSTAMP}.tar.gz"; then
     mkdir -p ${SNAPSHOTDIR} || true
-    cp alberta2-${DATE}.tar.bz2 geomview-${DATE}.tar.gz ${SNAPSHOTDIR}
-    rm -f `ls --color=no -C1 ${SNAPSHOTDIR}/*.gz|head -n -${NSNAPSHOTS}`
+    cp alberta2-${VERSTAMP}.tar.bz2 alberta2-${VERSTAMP}.tar.gz ${SNAPSHOTDIR}
+    rm -f `ls --color=no -C1 ${SNAPSHOTDIR}/*.tar.gz|head -n -${NSNAPSHOTS}`
+    rm -f `ls --color=no -C1 ${SNAPSHOTDIR}/*.tar.bz2|head -n -${NSNAPSHOTS}`
     chmod -R a+rX ${SNAPSHOTDIR}
 fi