diff --git a/t/t5900-repo-selection.sh b/t/t5900-repo-selection.sh
index 3d5b418bb4..14e59c5b3e 100755
--- a/t/t5900-repo-selection.sh
+++ b/t/t5900-repo-selection.sh
@@ -15,7 +15,7 @@ make_tree() {
 make_bare() {
 	git init --bare "$1" &&
 	(cd "$1" &&
-	 tree=`git hash-object -w -t tree /dev/null` &&
+	 tree=$(git hash-object -w -t tree /dev/null) &&
 	 commit=$(echo "$1" | git commit-tree $tree) &&
 	 git update-ref HEAD $commit
 	)