diff --git a/docker/horizon/Dockerfile.j2 b/docker/horizon/Dockerfile.j2
index 7f1a64f..8d25c49 100644
--- a/docker/horizon/Dockerfile.j2
+++ b/docker/horizon/Dockerfile.j2
@@ -1,4 +1,4 @@
-FROM {{ namespace }}/openstack-base:{{ tag }}
+FROM {{ image_spec("openstack-base") }}
 MAINTAINER {{ maintainer }}
 
 RUN apt-get update \