diff --git a/src/lhisp-oauth-client.ts b/src/lhisp-oauth-client.ts
index f18231b..213d8b4 100644
--- a/src/lhisp-oauth-client.ts
+++ b/src/lhisp-oauth-client.ts
@@ -21,7 +21,7 @@ export class LhispOauthClient<iAccessToken extends AccessToken = AccessToken> {
   protected authHeaderName: string;
   protected tokenHeaderName: string;
   protected authContentType: ContentType;
-  protected certificado?: string;
+  protected certificado?: string | Buffer;
   protected senhaCertificado?: string;
   protected authScope?: string;
   protected headers?: Headers;