diff --git a/requirements.txt b/requirements.txt
index 8770d94..3cdb602 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -68,7 +68,7 @@ multipledispatch==0.4.9
 nbconvert==4.2.0
 nbformat==4.2.0
 networkx==1.11
-nltk==3.2.2
+nltk==3.4.5
 nose==1.3.7
 notebook==4.3.1
 numba==0.30.1