diff --git a/requirements.txt b/requirements.txt
index 79dbce5..d20edcc 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -3,6 +3,7 @@ gensim==1.0.1
 nltk==3.2.5
 numpy==1.14.0
 pandas==0.19.2
+Cython==0.28.2
 pyjnius==1.1.1
 scikit-learn==0.19.1
 scipy==1.0.0