diff --git a/requirements.txt b/requirements.txt
index b16ef668..9f26c8c3 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -2,7 +2,7 @@ pbr!=2.1.0,>=2.0.0 # Apache-2.0
 
 jinja2>=2.9
 ansible>=2.2.0.0,!=2.4.0.0
-Flask>=0.11,<0.13
+Flask>=0.11,<0.13,!=0.12.3
 Flask-SQLAlchemy
 Flask-Migrate
 Flask-Script