diff --git a/test/sharness.sh b/test/sharness.sh
index ace5a5b5..ac13b7b6 100644
--- a/test/sharness.sh
+++ b/test/sharness.sh
@@ -895,7 +895,7 @@ SHARNESS_TEST_FILE="$0"
 export SHARNESS_TEST_FILE
 
 # Prepare test area.
-SHARNESS_TRASH_DIRECTORY="trash directory.$(basename "$SHARNESS_TEST_FILE" ".$SHARNESS_TEST_EXTENSION")"
+SHARNESS_TRASH_DIRECTORY="trash_directory.$(basename "$SHARNESS_TEST_FILE" ".$SHARNESS_TEST_EXTENSION")"
 test -n "$root" && SHARNESS_TRASH_DIRECTORY="$root/$SHARNESS_TRASH_DIRECTORY"
 case "$SHARNESS_TRASH_DIRECTORY" in
 /*) ;; # absolute path is good