diff --git a/.forgejo/workflows/lint-and-build.yml b/.forgejo/workflows/lint-and-build.yml
index 61e15be..ea85199 100644
--- a/.forgejo/workflows/lint-and-build.yml
+++ b/.forgejo/workflows/lint-and-build.yml
@@ -111,8 +111,12 @@ jobs:
         image: mongo:7
         env:
           MONGO_INITDB_DATABASE: normogen_test
-        ports:
-          - 27017:27017
+        # No `ports:` mapping: the job container reaches Mongo over the job's
+        # internal network via the service hostname (MONGODB_URI uses `mongo`,
+        # not localhost). Publishing to a host port is unnecessary and collides
+        # with any mongod already bound to :27017 on the runner host — which
+        # made the service container fail to schedule ("port is already
+        # allocated") and aborted the whole test job before any test ran.
     env:
       MONGODB_URI: mongodb://mongo:27017
       APP_ENVIRONMENT: development