diff --git a/requirements(ref).txt b/requirements(ref).txt
index 71960d7..25d1044 100644
--- a/requirements(ref).txt
+++ b/requirements(ref).txt
@@ -1,4 +1,4 @@
-nltk==3.3
+nltk==3.6.3
 numpy==1.16.4
 tensorflow==1.12.0
 tflearn==0.3.2
diff --git a/requirements.txt b/requirements.txt
index 009bed0..5feec55 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -63,7 +63,7 @@ mistune==0.8.4
 mock==4.0.2
 nbconvert==5.6.1
 nbformat==5.0.6
-nltk==3.5
+nltk==3.6.3
 numpy==1.16.4
 oauth2client==4.1.3
 oauthlib==3.1.0