diff --git a/src/controller/authorization.ts b/src/controller/authorization.ts
index 4f5c224..7129f99 100644
--- a/src/controller/authorization.ts
+++ b/src/controller/authorization.ts
@@ -100,9 +100,11 @@ export const authorization = wrap(async (req, res) => {
   }
 
   // TODO: multiple redirect URI
-  if (!oauth2.model.client.getRedirectUri(client)) {
+  if (!(await oauth2.model.client.hasRedirectUri(client))) {
     throw new UnsupportedResponseType('The client has not set a redirect uri');
-  } else if (!oauth2.model.client.checkRedirectUri(client, redirectUri)) {
+  } else if (
+    !(await oauth2.model.client.checkRedirectUri(client, redirectUri))
+  ) {
     throw new InvalidRequest('Wrong RedirectUri provided');
   }
   req.oauth2.logger.debug('redirect_uri check passed');
diff --git a/src/model/model.ts b/src/model/model.ts
index e7c60ea..81511ab 100644
--- a/src/model/model.ts
+++ b/src/model/model.ts
@@ -19,7 +19,7 @@ export interface OAuth2AccessToken {
   user_id: string | number;
   client_id: string | number;
   scope: string;
-  expires_at: number;
+  expires_at: Date;
 }
 
 /**
@@ -27,7 +27,7 @@ export interface OAuth2AccessToken {
  */
 export interface OAuth2Code {
   code: string;
-  expires_at: number;
+  expires_at: Date;
   user_id: string | number;
   client_id: string | number;
   scope: string;
@@ -140,12 +140,15 @@ export interface OAuth2ClientAdapter {
   /**
    * Get the redirect uri of a client
    */
-  getRedirectUri: (client: OAuth2Client) => string;
+  hasRedirectUri: (client: OAuth2Client) => Promise<boolean>;
 
   /**
    * Check the redirect uri against a client
    */
-  checkRedirectUri: (client: OAuth2Client, redirectUri: string) => boolean;
+  checkRedirectUri: (
+    client: OAuth2Client,
+    redirectUri: string
+  ) => Promise<boolean>;
 
   /**
    * Transform the scope into a string array of scopes