diff --git a/CHANGES.md b/CHANGES.md
index d7ad115f..16bdf2af 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -8,6 +8,7 @@
 
 * Fix Events shutdown (a manual start-up is required after updating to this fix)
 * Add free space stat (if obtainable) of parent folder(s) to footer
+* Add 'PB', 'EB', 'ZB', 'YB' to recognised output sizes
 
 
 ### 0.13.10 (2018-01-08 17:20:00 UTC)
diff --git a/sickbeard/helpers.py b/sickbeard/helpers.py
index b856ebaf..2575b318 100644
--- a/sickbeard/helpers.py
+++ b/sickbeard/helpers.py
@@ -275,7 +275,7 @@ def searchIndexerForShowID(regShowName, indexer=None, indexer_id=None, ui=None):
 
 
 def sizeof_fmt(num):
-    for x in ['bytes', 'KB', 'MB', 'GB', 'TB']:
+    for x in ['bytes', 'KB', 'MB', 'GB', 'TB', 'PB', 'EB', 'ZB', 'YB']:
         if num < 1024.0:
             return "%3.1f %s" % (num, x)
         num /= 1024.0