diff --git a/requirements.txt b/requirements.txt
index cd296fa..b722009 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,5 +1,5 @@
 spacy==2.1.3
-nltk==3.2.1
+nltk==3.6.6
 rdflib==4.2.2
 yappi==1.0
 gensim==3.7.2
diff --git a/setup.py b/setup.py
index f60f3f6..83c0d6e 100644
--- a/setup.py
+++ b/setup.py
@@ -28,7 +28,7 @@
                 ],
       install_requires=[
           'spacy==2.1.3',
-          'nltk==3.2.1',
+          'nltk==3.6.6',
           'rdflib==4.2.2',
           'yappi==1.0',
           'gensim==3.7.2',