diff --git a/doc/build.py b/doc/build.py
index f8238195..69b0a38c 100755
--- a/doc/build.py
+++ b/doc/build.py
@@ -11,7 +11,7 @@ def pip_install(package, commit=None, **kwargs):
   if commit:
     package = 'git+git://github.com/{0}.git@{1}'.format(package, commit)
   print('Installing {}'.format(package))
-  check_call(['pip', 'install', '--upgrade', package])
+  check_call(['pip', 'install', package])
 
 def create_build_env():
   # Create virtualenv.
@@ -42,7 +42,7 @@ def create_build_env():
   # Install Sphinx and Breathe.
   pip_install('sphinx-doc/sphinx',
               '12b83372ac9316e8cbe86e7fed889296a4cc29ee',
-              check_version='1.4a0.dev-20151013')
+              check_version='1.4.1.dev20160525')
   pip_install('michaeljones/breathe',
               '6b1c5bb7a1866f15fc328b8716258354b10c1daa')