diff --git a/requirements.txt b/requirements.txt
index cbfc58ab6df8694fc298a5a3ad4e0f9c7686ce71..3115651185ed0efa96d72e4b02b05347fac62424 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,3 +1,4 @@
+graphviz
 matplotlib
 nltk
 pandas