diff --git a/zuul.d/ironic-python-agent-jobs.yaml b/zuul.d/ironic-python-agent-jobs.yaml
index 6b17d9f79..36918fe07 100644
--- a/zuul.d/ironic-python-agent-jobs.yaml
+++ b/zuul.d/ironic-python-agent-jobs.yaml
@@ -102,12 +102,18 @@
     parent: ironic-python-agent-buildimage-base
     vars:
       image_name: 'coreos'
+      # TODO(dtantsur): refactor run.yaml, so that this variable is only
+      # required for DIB jobs.
+      image_distro: ''
 
 - job:
     name: ironic-python-agent-buildimage-tinyipa
     parent: ironic-python-agent-buildimage-base
     vars:
       image_name: 'tinyipa'
+      # TODO(dtantsur): refactor run.yaml, so that this variable is only
+      # required for DIB jobs.
+      image_distro: ''
 
 - job:
     name: ironic-python-agent-buildimage-dib