--- a/setup.py
+++ b/setup.py
@@ -15,10 +15,5 @@
     license="Licensed under the GNU GPL v3+.",
     packages=['urwidtrees'],
     install_requires=['urwid>=1.1.0'],
-    extras_require={
-        'docs': [
-            'mock;python_version<"3.3"',
-        ],
-    },
 )
 
--- a/urwidtrees.egg-info/requires.txt
+++ b/urwidtrees.egg-info/requires.txt
@@ -3,4 +3,3 @@
 [docs]
 
 [docs:python_version < "3.3"]
-mock
