diff --git a/alibaba_suanfa.egg-info/requires.txt b/alibaba_suanfa.egg-info/requires.txt
index f6b137e..60fc729 100644
--- a/alibaba_suanfa.egg-info/requires.txt
+++ b/alibaba_suanfa.egg-info/requires.txt
@@ -1,2 +1,2 @@
-nltk==3.4.5
+nltk==3.9
 scikit-learn==0.20.2
diff --git a/setup.py b/setup.py
index 6900d3d..71f0a4a 100644
--- a/setup.py
+++ b/setup.py
@@ -34,7 +34,7 @@
         'Topic :: Software Development :: Libraries'
     ],
     install_requires=[
-        'nltk==3.4.5',
+        'nltk==3.9',
         'scikit-learn==0.20.2',
     ]
 )