diff --git a/tools/gate/roles/build-images/tasks/airship-shipyard.yaml b/tools/gate/roles/build-images/tasks/airship-shipyard.yaml
index 379b0d58..6a15e313 100644
--- a/tools/gate/roles/build-images/tasks/airship-shipyard.yaml
+++ b/tools/gate/roles/build-images/tasks/airship-shipyard.yaml
@@ -26,10 +26,10 @@
 - name: Determine tags
   shell: echo '{{ tags | to_json }}' | python {{ zuul.project.src_dir }}/tools/image_tags.py
   environment:
-    BRANCH: "{{ zuul.branch }}"
-    CHANGE: "{{ zuul.change }}"
+    BRANCH: "{{ zuul.branch | default('') }}"
+    CHANGE: "{{ zuul.change | default('') }}"
     COMMIT: "{{ zuul.newrev | default('') }}"
-    PATCHSET: "{{ zuul.patchset }}"
+    PATCHSET: "{{ zuul.patchset | default('') }}"
   register: image_tags
 
 - name: Debug computed tags