diff --git a/lib/Lacuna/RPC/Building/MissionCommand.pm b/lib/Lacuna/RPC/Building/MissionCommand.pm
index 9ce690f3..c9d8556b 100644
--- a/lib/Lacuna/RPC/Building/MissionCommand.pm
+++ b/lib/Lacuna/RPC/Building/MissionCommand.pm
@@ -59,7 +59,7 @@ sub complete_mission {
     # this check is repeated later to avoid race conditions, but done early
     # to give more meaningful errors to those not trying to game the system.
     confess [1002, 'Already completed that mission in another zone.']
-        if Lacuna->cache->get($mission->mission_file_name, $empire->empire_id);
+        if Lacuna->cache->get($mission->mission_file_name, $empire->id);
     my $body = $building->body;
     $mission->check_objectives($body);
     $mission->complete($body);