diff --git a/conda-requirements.txt b/conda-requirements.txt
index 63c718c557..b1b6421f5b 100644
--- a/conda-requirements.txt
+++ b/conda-requirements.txt
@@ -17,7 +17,7 @@ setuptools
 cfchecker
 mock
 nose
-pep8
+pep8=1.5.7
 sphinx
 
 # Optional iris dependencies