diff --git a/README.md b/README.md
index e4d8718b9d..ae8f427dba 100644
--- a/README.md
+++ b/README.md
@@ -1,6 +1,7 @@
 [![Documentation Status](https://readthedocs.org/projects/arch/badge/?version=latest)](http://arch.readthedocs.org/en/latest/)
 [![CI Status](https://travis-ci.org/bashtage/arch.svg?branch=master)](https://travis-ci.org/bashtage/arch)
 [![Coverage Status](https://coveralls.io/repos/bashtage/arch/badge.png?branch=master)](https://coveralls.io/r/bashtage/arch?branch=master)
+[![DOI](https://zenodo.org/badge/doi/10.5281/zenodo.15681.svg)](http://dx.doi.org/10.5281/zenodo.15681)
 
 # ARCH
 
diff --git a/doc/requirements.txt b/doc/requirements.txt
index bd5dc350b5..7c09c77042 100644
--- a/doc/requirements.txt
+++ b/doc/requirements.txt
@@ -1,5 +1,3 @@
-sphinxcontrib-napoleon
-mock
 numpy
 Cython
 scipy
@@ -8,4 +6,5 @@ pandas
 patsy
 ipython
 statsmodels
-
+sphinxcontrib-napoleon==0.2.11
+mock