diff --git a/.travis.yml b/.travis.yml
index 1b6f68f..c847910 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -22,7 +22,7 @@ compiler: gcc
 before_install:
   - buildutils/setup_travis.sh
   - travis_retry pip install -U setuptools
-  - travis_retry pip install cython
+  - travis_retry pip install cython==0.21.2
   - travis_retry pip install pytest
 
 install:
diff --git a/requirements.txt b/requirements.txt
index 617ceb5..8712fde 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,5 +1,5 @@
 jinja2 >= 2.7.3
-cython >= 0.21
+cython == 0.21.2
 setuptools >= 0.8
 pytest
 tox