diff --git a/requirements.txt b/requirements.txt
index 4fa5f4e..3f9c689 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -9,4 +9,4 @@ pecan>=1.0.0 # BSD
 WSME>=0.8 # MIT
 oslo.config>=3.9.0 # Apache-2.0
 python-keystoneclient!=1.8.0,!=2.1.0,>=1.7.0 # Apache-2.0
-Flask<1.0,>=0.10 # BSD
+Flask!=0.11,<1.0,>=0.10 # BSD