diff -r 0a638f37f2d2 -r 59c135bb31bc hgext/blackbox.py
--- a/hgext/blackbox.py	Sat Jun 17 13:21:06 2017 +0200
+++ b/hgext/blackbox.py	Sun Jun 18 20:49:08 2017 +0200
@@ -62,7 +62,7 @@
 configitem = registrar.configitem(configtable)
 
 configitem('blackbox', 'maxsize',
-    default=1048576,
+    default='1 MB',
 )
 
 lastui = None