diff --git a/config/prod.js b/config/prod.js
index dce5641..a9e1b85 100644
--- a/config/prod.js
+++ b/config/prod.js
@@ -12,7 +12,7 @@ module.exports = {
         scopes: 'openid profile',
         grantTypes: process.env.OIDC_GRANT_TYPES,
         signedResponseAlg: process.env.OIDC_ID_TOKEN_SIGNED_RESPONSE_ALG,
-        codeChallengeMethod: 'RS256',
+        codeChallengeMethod: 'S256',
         responseTypes: process.env.OIDC_RESPONSE_TYPES,
         authMethod: process.env.OIDC_TOKEN_ENDPOINT_AUTH_METHOD,
     },