diff --git a/src/systemd_resolved_docker/dockerwatcher.py b/src/systemd_resolved_docker/dockerwatcher.py
index ae9937fa0cafe26843db8fc75e07f484867e37f2..aae6d15cb61d688738aa4c0b6685766b8a5a2277 100644
--- a/src/systemd_resolved_docker/dockerwatcher.py
+++ b/src/systemd_resolved_docker/dockerwatcher.py
@@ -51,7 +51,7 @@ class DockerWatcher(Thread):
 
             # if no explicit --hostname is provided, than it will be the first 12 characters of the container_id.
             # In that case, the hostname can be ignored
-            if hostname not in container_id:
+            if hostname != container_id[:12]:
                 if len(domain) > 0:
                     common_hostnames.append('%s.%s' % (hostname, domain))
                 else: