diff --git a/src/keycloak/keycloak_openid.py b/src/keycloak/keycloak_openid.py
index c8bf745..5eb2f8e 100644
--- a/src/keycloak/keycloak_openid.py
+++ b/src/keycloak/keycloak_openid.py
@@ -1654,7 +1654,7 @@ class KeycloakOpenID:
         if validate:
             if key is None:
                 key = jwk.JWKSet()
-                for cert in self.certs()["keys"]:
+                for cert in (await self.a_certs())["keys"]:
                     key.add(jwk.JWK(**cert))
         else:
             key = None