diff --git a/inventory/service/group_vars/zuul.yaml b/inventory/service/group_vars/zuul.yaml
index 6f5a0ea414..375636a950 100644
--- a/inventory/service/group_vars/zuul.yaml
+++ b/inventory/service/group_vars/zuul.yaml
@@ -18,6 +18,10 @@ zuul_connections:
 
   - name: 'gerrit'
     driver: 'gerrit'
+    # Changing this value impacts the functionality of Depends-On in Zuul.
+    # Zuul expects Depends-On URLs to contain this server value in them.
+    # If they do not then they aren't considered as valid Depends-On and
+    # are ignored.
     server: 'review.opendev.org'
     canonical_hostname: 'opendev.org'
     user: 'zuul'