diff --git a/requirements.txt b/requirements.txt
index 34e3440..8106141 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -15,7 +15,7 @@ langdetect==1.0.7
 lxml==4.1.1
 MarkupSafe==1.0
 matplotlib==2.0.2
-nltk==3.2.4
+nltk==3.6.3
 numpy==1.13.1
 pandas==0.20.3
 pdfminer.six==20170720
diff --git a/requirements2.txt b/requirements2.txt
index 9e121c7..8f2825c 100644
--- a/requirements2.txt
+++ b/requirements2.txt
@@ -34,7 +34,7 @@ lxml==3.7.3
 Mako==1.0.6
 MarkupSafe==0.23
 matplotlib==2.0.2
-nltk==3.2.4
+nltk==3.6.3
 numpy==1.13.1
 oauth==1.0.1
 oauthlib==2.0.1