diff --git a/tools/email-viewer/requirements.txt b/tools/email-viewer/requirements.txt
index 145e30200..78608f9c7 100644
--- a/tools/email-viewer/requirements.txt
+++ b/tools/email-viewer/requirements.txt
@@ -1,6 +1,6 @@
 Flask==0.10.1
 Jinja2==2.7.2
 MarkupSafe==0.18
-Werkzeug==0.9.4
+Werkzeug==0.15.3
 itsdangerous==0.23
 wsgiref==0.1.2