diff --git a/t/test-lib.sh b/t/test-lib.sh
index af722d383d..92d0db13d7 100644
--- a/t/test-lib.sh
+++ b/t/test-lib.sh
@@ -1577,6 +1577,8 @@ fi
 # Use -P to resolve symlinks in our working directory so that the cwd
 # in subprocesses like git equals our $PWD (for pathname comparisons).
 cd -P "$TRASH_DIRECTORY" || BAIL_OUT "cannot cd -P to \"$TRASH_DIRECTORY\""
+TRASH_DIRECTORY=$(pwd)
+HOME="$TRASH_DIRECTORY"
 
 start_test_output "$0"