diff --git a/src/lib.rs b/src/lib.rs
index 5b861a5..0cdd757 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -148,7 +148,7 @@ struct OidcQuery {
     code: String,
     state: String,
     #[allow(dead_code)]
-    session_state: String,
+    session_state: Option<String>,
 }
 
 /// oidc session