diff --git a/diskutil.c b/diskutil.c
index e90096b..92f8caa 100644
--- a/diskutil.c
+++ b/diskutil.c
@@ -67,10 +67,10 @@
 	struct disk_util_stat __dus, *dus, *ldus;
 	struct timeval t;
 
-	if (get_io_ticks(du, &__dus))
-		return;
 	if (!du->users)
 		return;
+	if (get_io_ticks(du, &__dus))
+		return;
 
 	dus = &du->dus;
 	ldus = &du->last_dus;