diff --git a/lib/src/model/auth/authentication_data.dart b/lib/src/model/auth/authentication_data.dart
index 1f4cfc31..02633ca3 100644
--- a/lib/src/model/auth/authentication_data.dart
+++ b/lib/src/model/auth/authentication_data.dart
@@ -22,6 +22,8 @@
 */
 
 class AuthenticationData {
+  // Should be non-nullable according to the spec but this leads to this problem
+  // https://github.com/matrix-org/matrix-doc/issues/3370
   String? type;
   String? session;