diff --git a/mongo/oplog_test.go b/mongo/oplog_test.go
index <HASH>..<HASH> 100644
--- a/mongo/oplog_test.go
+++ b/mongo/oplog_test.go
@@ -239,11 +239,7 @@ func (s *oplogSuite) startMongoWithReplicaset(c *gc.C) (*jujutesting.MgoInstance
 }
 
 func (s *oplogSuite) startMongo(c *gc.C) (*jujutesting.MgoInstance, *mgo.Session) {
-	inst := &jujutesting.MgoInstance{
-		Params: []string{
-			"--setParameter", "enableTestCommands=1", // allows "emptycapped" command
-		},
-	}
+	inst := &jujutesting.MgoInstance{}
 	err := inst.Start(nil)
 	c.Assert(err, jc.ErrorIsNil)
 	s.AddCleanup(func(*gc.C) { inst.Destroy() })
Stop passing enableTestCommands=1 to mongo

It's always passed by testing/mgo now.