diff --git a/autogen.sh b/autogen.sh
index de5d14eba..88f7b9bda 100755
--- a/autogen.sh
+++ b/autogen.sh
@@ -7,8 +7,13 @@ srcdir=`dirname "$0"`
 # sed program
 SED=${SED-sed}
 
+# If GIT_DIR is set, use it. If not, try ".git".
+if test -n "$GIT_DIR"; then :;
+else GIT_DIR=".git"; export GIT_DIR
+fi
+
 # Check whether the version needs to be updated from VCS/version-stamp
-if [ -d ".git" ] && [ -d "autom4te.cache" ]; then
+if [ -d "$GIT_DIR" ] && [ -d "autom4te.cache" ]; then
   git_describe=`./build-utils/package-version . version-stamp`
   for f in autom4te.cache/output.*; do
     [ -f "$f" ] || continue
diff --git a/build-utils/package-version b/build-utils/package-version
index 6a1858c7d..6c8bc3543 100755
--- a/build-utils/package-version
+++ b/build-utils/package-version
@@ -12,10 +12,15 @@ test -d "$top_srcdir" || { \
 }
 version_stamp="${2-version-stamp}"
 
+# If GIT_DIR is set, use it. If not, try top_srcdir/.git.
+if test -n "$GIT_DIR"; then :;
+else GIT_DIR="$top_srcdir/.git"; export GIT_DIR
+fi
+
 if test -f "$top_srcdir/$version_stamp"; then # dist source tree
 	cat "$top_srcdir/$version_stamp" | ${TR-tr} -d '\012'
-elif test -d "$top_srcdir/.git"; then # git source tree
-	git_describe=`${GIT-git} --git-dir="$top_srcdir/.git" describe 2>/dev/null || echo devel`
+elif test -d "$GIT_DIR"; then # git source tree
+	git_describe=`${GIT-git} describe 2>/dev/null || echo devel`
 	echo "$git_describe" | ${SED-sed} -e 's/^v//' -e 's/-/./g' | ${TR-tr} -d '\012'
 else # ???
 	echo "devel" | ${TR-tr} -d '\012'