diff --git a/requirement.txt b/requirement.txt
index 0c9177f..488e55c 100644
--- a/requirement.txt
+++ b/requirement.txt
@@ -107,7 +107,7 @@ navigator-updater==0.2.1
 nbconvert==5.4.0
 nbformat==4.4.0
 networkx==2.2
-nltk==3.4
+nltk==3.4.5
 nose==1.3.7
 notebook==5.7.4
 numba==0.41.0