diff --git a/requirements.txt b/requirements.txt
index 4b2294b..779a4ea 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -21,7 +21,7 @@ kiwisolver==1.0.1
 Lasagne==0.2.dev1
 lxml==4.3.2
 matplotlib==2.2.3
-nltk==3.4
+nltk==3.6.3
 numpy==1.15.4
 parse==1.9.0
 progressbar==2.5
diff --git a/requirements3.txt b/requirements3.txt
index c250770..db78089 100644
--- a/requirements3.txt
+++ b/requirements3.txt
@@ -76,7 +76,7 @@ msgpack==0.5.6
 msgpack-numpy==0.4.3.2
 murmurhash==1.0.2
 networkx==1.11
-nltk==3.4
+nltk==3.6.3
 nose==1.3.7
 numpy==1.16.2
 numpydoc==0.8.0