diff --git a/packages/source/ceilometer/doc/requirements.txt b/packages/source/ceilometer/doc/requirements.txt
index b2865a0..b038ddc 100644
--- a/packages/source/ceilometer/doc/requirements.txt
+++ b/packages/source/ceilometer/doc/requirements.txt
@@ -8,6 +8,6 @@ argparse
 sqlalchemy
 eventlet
 anyjson>=0.3.1
-Flask==0.9
+Flask==1.0
 sphinxcontrib-httpdomain
 pymongo>=2.2.1