diff --git a/git-filter-branch.sh b/git-filter-branch.sh
index 333f6a8..80e99e5 100755
--- a/git-filter-branch.sh
+++ b/git-filter-branch.sh
@@ -435,11 +435,17 @@
 trap - 0
 
 unset GIT_DIR GIT_WORK_TREE GIT_INDEX_FILE
-test -z "$ORIG_GIT_DIR" || GIT_DIR="$ORIG_GIT_DIR" && export GIT_DIR
-test -z "$ORIG_GIT_WORK_TREE" || GIT_WORK_TREE="$ORIG_GIT_WORK_TREE" &&
+test -z "$ORIG_GIT_DIR" || {
+	GIT_DIR="$ORIG_GIT_DIR" && export GIT_DIR
+}
+test -z "$ORIG_GIT_WORK_TREE" || {
+	GIT_WORK_TREE="$ORIG_GIT_WORK_TREE" &&
 	export GIT_WORK_TREE
-test -z "$ORIG_GIT_INDEX_FILE" || GIT_INDEX_FILE="$ORIG_GIT_INDEX_FILE" &&
+}
+test -z "$ORIG_GIT_INDEX_FILE" || {
+	GIT_INDEX_FILE="$ORIG_GIT_INDEX_FILE" &&
 	export GIT_INDEX_FILE
+}
 git read-tree -u -m HEAD
 
 exit $ret