diff --git a/src/externalldap.js b/src/externalldap.js
index dbf36a40c..9f374209b 100644
--- a/src/externalldap.js
+++ b/src/externalldap.js
@@ -291,10 +291,7 @@ async function verifyPassword(user, password) {
 
     const client = await getClient(externalLdapConfig, { bind: false });
 
-    // create a separate function on the instance so we can call the promisified version with the correct this pointer
-    client.bindPromisified = util.promisify(client.bind);
-
-    const [error] = await safe(client.bindPromisified(ldapUsers[0].dn, password));
+    const [error] = await safe(util.promisify(client.bind.bind(client))(ldapUsers[0].dn, password));
     client.unbind();
     if (error instanceof ldap.InvalidCredentialsError) throw new BoxError(BoxError.INVALID_CREDENTIALS);
     if (error) throw new BoxError(BoxError.EXTERNAL_ERROR, error);