diff --git a/src/index.ts b/src/index.ts
index f3b9a3c..842b756 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -285,7 +285,7 @@ export default class NodeFacebook {
     return this.config.redirect_uri;
   }
 
-  private normalizeUrl(rawUrl: string, params?: ParsedUrlQueryInput) {
+  private normalizeUrl(rawUrl: string, params: ParsedUrlQueryInput = {}) {
     const query = params as {
       access_token: string;
       appsecret_proof: string;