diff --git a/src/mdtest.c b/src/mdtest.c
index 540418c..a0922ff 100644
--- a/src/mdtest.c
+++ b/src/mdtest.c
@@ -2134,6 +2134,7 @@ void mdtest_init_args(){
    unique_dir_per_task = 0;
    time_unique_dir_overhead = 0;
    items = 0;
+   num_dirs_in_tree_calc = 0;
    collective_creates = 0;
    write_bytes = 0;
    stone_wall_timer_seconds = 0;