diff --git a/pkg/backup.go b/pkg/backup.go
index 0ca48f731..8115e6042 100644
--- a/pkg/backup.go
+++ b/pkg/backup.go
@@ -396,7 +396,7 @@ func (opt *mongoOptions) backupMongoDB(targetRef api_v1beta1.TargetRef) (*restic
 		dumpCreds = append(dumpCreds, []interface{}{
 			fmt.Sprintf("--username=%s", username),
 			fmt.Sprintf("--password=%s", authSecret.Data[MongoPasswordKey]),
-			"--authenticationDatabase", opt.authenticationDatabase,
+			fmt.Sprintf("--authenticationDatabase=%s", opt.authenticationDatabase),
 		}...)
 
 	} else {
@@ -413,7 +413,7 @@ func (opt *mongoOptions) backupMongoDB(targetRef api_v1beta1.TargetRef) (*restic
 		dumpCreds = append(dumpCreds, []interface{}{
 			fmt.Sprintf("--username=%s", username),
 			fmt.Sprintf("--password=%s", authSecret.Data[MongoPasswordKey]),
-			"--authenticationDatabase", opt.authenticationDatabase,
+			fmt.Sprintf("--authenticationDatabase=%s", opt.authenticationDatabase),
 		}...)
 	}