diff --git a/API/requirements.txt b/API/requirements.txt
index f8dd4f5..674acf2 100644
--- a/API/requirements.txt
+++ b/API/requirements.txt
@@ -2,5 +2,5 @@ scikit-learn==0.20.1
 Flask==1.0.2
 rdflib==4.2.2
 validators==0.13.0
-nltk==3.4
+nltk==3.6.6
 numpy==1.15.4
\ No newline at end of file