diff --git a/types/mongodb/index.d.ts b/types/mongodb/index.d.ts
index 1ac38c79d5..e516e4d31f 100644
--- a/types/mongodb/index.d.ts
+++ b/types/mongodb/index.d.ts
@@ -283,9 +283,9 @@ export interface MongoClientOptions extends
      useNewUrlParser?: boolean;
 
     /**
-     * Mechanism for authentication: MDEFAULT, GSSAPI, PLAIN, MONGODB-X509, or SCRAM-SHA-1
+     * Mechanism for authentication: DEFAULT, GSSAPI, PLAIN, MONGODB-X509, 'MONGODB-CR', SCRAM-SHA-1 or SCRAM-SHA-256
      */
-    authMechanism?: 'MDEFAULT' | 'GSSAPI' | 'PLAIN' | 'MONGODB-X509' | 'SCRAM-SHA-1' | string;
+    authMechanism?: 'DEFAULT' | 'GSSAPI' | 'PLAIN' | 'MONGODB-X509' | 'MONGODB-CR' | 'SCRAM-SHA-1' | 'SCRAM-SHA-256' | string;
 }
 
 export interface SSLOptions {