diff --git a/tools/pip-requires b/tools/pip-requires
index bfc3330328..a337184ed4 100644
--- a/tools/pip-requires
+++ b/tools/pip-requires
@@ -32,7 +32,9 @@ lxml
 Paste
 
 passlib
-jsonschema
+# jsonschema pinned at <1 because of backwards incompatibility which breaks
+# the TestImagesDeserializerWithExtendedSchema unit tests.
+jsonschema<1
 python-keystoneclient>=0.2.0
 
 http://tarballs.openstack.org/oslo-config/oslo-config-2013.1b4.tar.gz#egg=oslo-config