diff --git a/t/unit-tests/clar/clar/sandbox.h b/t/unit-tests/clar/clar/sandbox.h
index 7c177f3525870c..e25057b7c490e0 100644
--- a/t/unit-tests/clar/clar/sandbox.h
+++ b/t/unit-tests/clar/clar/sandbox.h
@@ -120,6 +120,12 @@ static int build_sandbox_path(void)
 	if (_mktemp(_clar_path) == NULL)
 		return -1;
 
+	if (mkdir(_clar_path, 0700) != 0)
+		return -1;
+#elif defined(__TANDEM)
+	if (mktemp(_clar_path) == NULL)
+		return -1;
+
 	if (mkdir(_clar_path, 0700) != 0)
 		return -1;
 #elif defined(_WIN32)