diff --git a/setup/start/collectd/du.py b/setup/start/collectd/du.py
index 4d10dd70d..3b34573be 100644
--- a/setup/start/collectd/du.py
+++ b/setup/start/collectd/du.py
@@ -6,7 +6,8 @@ PATHS = [] # { name, dir, exclude }
 INTERVAL = 60 * 60 * 12 # twice a day. change values in docker-graphite if you change this
 
 def du(pathinfo):
-    cmd = 'timeout 1800 du -Dsb "{}"'.format(pathinfo['dir'])
+    # -B1 makes du print block sizes and not apparent sizes (to match df which also uses block sizes)
+    cmd = 'timeout 1800 du -DsB1 "{}"'.format(pathinfo['dir'])
     if pathinfo['exclude'] != '':
         cmd += ' --exclude "{}"'.format(pathinfo['exclude'])