diff --git a/test/test-lib-common.sh b/test/test-lib-common.sh
index 03ef1d2d..178820bd 100644
--- a/test/test-lib-common.sh
+++ b/test/test-lib-common.sh
@@ -139,10 +139,7 @@ export PATH MANPATH
 # Test repository
 test="tmp.$(basename "$0" .sh)"
 test -n "$root" && test="$root/$test"
-case "$test" in
-/*) TMP_DIRECTORY="$test" ;;
- *) TMP_DIRECTORY="$TEST_DIRECTORY/$test" ;;
-esac
+TMP_DIRECTORY="$(mktemp -d)"
 test ! -z "$debug" || remove_tmp=$TMP_DIRECTORY
 rm -fr "$test" || {
 	GIT_EXIT_OK=t