Use "${var:?}" to ensure this never expands to /* .
diff --git a/third_party/ijar/test/ijar_test.sh b/third_party/ijar/test/ijar_test.sh
index 0b9a92f..5279f15 100755
--- a/third_party/ijar/test/ijar_test.sh
+++ b/third_party/ijar/test/ijar_test.sh
@@ -41,7 +41,7 @@
 source ${DIR}/testenv.sh || { echo "testenv.sh not found!" >&2; exit 1; }
 
 function cleanup() {
-  rm -fr "$TEST_TMPDIR"/*
+  rm -fr "${TEST_TMPDIR:-sentinel}"/*
 }
 
 trap cleanup EXIT