diff --git a/requirements.txt b/requirements.txt
index abdedbd..8ae7ae5 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -118,7 +118,7 @@ pydicom==0.9.9
 pydot2==1.0.33
 pydotplus==2.0.2
 pyflakes==1.1.0
-Pygments==2.1.3
+Pygments==2.7.4
 pyOpenSSL==16.0.0
 pyparsing==1.5.7
 pytest==2.8.5