diff --git a/lib/encryption.dart b/lib/encryption.dart
index f534f836..a71d1d70 100644
--- a/lib/encryption.dart
+++ b/lib/encryption.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2020, 2021 Famedly GmbH
diff --git a/lib/encryption/cross_signing.dart b/lib/encryption/cross_signing.dart
index 1447f65c..787bb0bc 100644
--- a/lib/encryption/cross_signing.dart
+++ b/lib/encryption/cross_signing.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2020, 2021 Famedly GmbH
diff --git a/lib/encryption/encryption.dart b/lib/encryption/encryption.dart
index 8b48539c..8add0b6b 100644
--- a/lib/encryption/encryption.dart
+++ b/lib/encryption/encryption.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2019, 2020, 2021 Famedly GmbH
diff --git a/lib/encryption/key_manager.dart b/lib/encryption/key_manager.dart
index 6d91d71e..86d93e18 100644
--- a/lib/encryption/key_manager.dart
+++ b/lib/encryption/key_manager.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2019, 2020, 2021 Famedly GmbH
diff --git a/lib/encryption/key_verification_manager.dart b/lib/encryption/key_verification_manager.dart
index 61a0b8c1..9185f436 100644
--- a/lib/encryption/key_verification_manager.dart
+++ b/lib/encryption/key_verification_manager.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2020, 2021 Famedly GmbH
diff --git a/lib/encryption/olm_manager.dart b/lib/encryption/olm_manager.dart
index ca9af24a..62290380 100644
--- a/lib/encryption/olm_manager.dart
+++ b/lib/encryption/olm_manager.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2019, 2020, 2021 Famedly GmbH
diff --git a/lib/encryption/ssss.dart b/lib/encryption/ssss.dart
index dd9c7a05..03cf66cd 100644
--- a/lib/encryption/ssss.dart
+++ b/lib/encryption/ssss.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2020, 2021 Famedly GmbH
diff --git a/lib/encryption/utils/bootstrap.dart b/lib/encryption/utils/bootstrap.dart
index 843489d2..3dcd1533 100644
--- a/lib/encryption/utils/bootstrap.dart
+++ b/lib/encryption/utils/bootstrap.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2020, 2021 Famedly GmbH
diff --git a/lib/encryption/utils/json_signature_check_extension.dart b/lib/encryption/utils/json_signature_check_extension.dart
index 7c89bca8..b2505d5d 100644
--- a/lib/encryption/utils/json_signature_check_extension.dart
+++ b/lib/encryption/utils/json_signature_check_extension.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2020, 2021 Famedly GmbH
diff --git a/lib/encryption/utils/key_verification.dart b/lib/encryption/utils/key_verification.dart
index eab46153..1c3c89a6 100644
--- a/lib/encryption/utils/key_verification.dart
+++ b/lib/encryption/utils/key_verification.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2020, 2021 Famedly GmbH
diff --git a/lib/encryption/utils/olm_session.dart b/lib/encryption/utils/olm_session.dart
index 99592b9c..5d97e95a 100644
--- a/lib/encryption/utils/olm_session.dart
+++ b/lib/encryption/utils/olm_session.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2020, 2021 Famedly GmbH
diff --git a/lib/encryption/utils/outbound_group_session.dart b/lib/encryption/utils/outbound_group_session.dart
index 90baef54..7328577c 100644
--- a/lib/encryption/utils/outbound_group_session.dart
+++ b/lib/encryption/utils/outbound_group_session.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2019, 2020, 2021 Famedly GmbH
diff --git a/lib/encryption/utils/session_key.dart b/lib/encryption/utils/session_key.dart
index cf031ef0..c9e3be80 100644
--- a/lib/encryption/utils/session_key.dart
+++ b/lib/encryption/utils/session_key.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2019, 2020, 2021 Famedly GmbH
diff --git a/lib/encryption/utils/ssss_cache.dart b/lib/encryption/utils/ssss_cache.dart
index 9ec71a9f..e14aad77 100644
--- a/lib/encryption/utils/ssss_cache.dart
+++ b/lib/encryption/utils/ssss_cache.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2021 Famedly GmbH
diff --git a/lib/encryption/utils/stored_inbound_group_session.dart b/lib/encryption/utils/stored_inbound_group_session.dart
index 71c821d6..e9ac0a8e 100644
--- a/lib/encryption/utils/stored_inbound_group_session.dart
+++ b/lib/encryption/utils/stored_inbound_group_session.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2021 Famedly GmbH
diff --git a/lib/matrix.dart b/lib/matrix.dart
index 01339c0b..90dd0234 100644
--- a/lib/matrix.dart
+++ b/lib/matrix.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2019, 2020, 2021 Famedly GmbH
diff --git a/lib/src/client.dart b/lib/src/client.dart
index f0349e8c..45ae727d 100644
--- a/lib/src/client.dart
+++ b/lib/src/client.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2019, 2020, 2021 Famedly GmbH
diff --git a/lib/src/database/database_api.dart b/lib/src/database/database_api.dart
index 8686b96f..d1065ad3 100644
--- a/lib/src/database/database_api.dart
+++ b/lib/src/database/database_api.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2021 Famedly GmbH
diff --git a/lib/src/database/hive_database.dart b/lib/src/database/hive_database.dart
index d0832e2e..92c2f030 100644
--- a/lib/src/database/hive_database.dart
+++ b/lib/src/database/hive_database.dart
@@ -1,3 +1,22 @@
+// @dart=2.9
+/*
+ *   Famedly Matrix SDK
+ *   Copyright (C) 2019, 2020, 2021 Famedly GmbH
+ *
+ *   This program is free software: you can redistribute it and/or modify
+ *   it under the terms of the GNU Affero General Public License as
+ *   published by the Free Software Foundation, either version 3 of the
+ *   License, or (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ *   GNU Affero General Public License for more details.
+ *
+ *   You should have received a copy of the GNU Affero General Public License
+ *   along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
 import 'dart:async';
 import 'dart:convert';
 import 'dart:math';
diff --git a/lib/src/event.dart b/lib/src/event.dart
index 03460610..ffdb006c 100644
--- a/lib/src/event.dart
+++ b/lib/src/event.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2019, 2020, 2021 Famedly GmbH
diff --git a/lib/src/room.dart b/lib/src/room.dart
index 0a695eda..09d5a5da 100644
--- a/lib/src/room.dart
+++ b/lib/src/room.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2019, 2020, 2021 Famedly GmbH
diff --git a/lib/src/timeline.dart b/lib/src/timeline.dart
index e314b603..76ccff27 100644
--- a/lib/src/timeline.dart
+++ b/lib/src/timeline.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2019, 2020, 2021 Famedly GmbH
diff --git a/lib/src/user.dart b/lib/src/user.dart
index b3c836d9..cc639684 100644
--- a/lib/src/user.dart
+++ b/lib/src/user.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2019, 2020, 2021 Famedly GmbH
diff --git a/lib/src/utils/QueuedToDeviceEvent.dart b/lib/src/utils/QueuedToDeviceEvent.dart
index 6f076427..bf4296f7 100644
--- a/lib/src/utils/QueuedToDeviceEvent.dart
+++ b/lib/src/utils/QueuedToDeviceEvent.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2019, 2020 Famedly GmbH
diff --git a/lib/src/utils/commands_extension.dart b/lib/src/utils/commands_extension.dart
index 820cf9dc..a5cf153b 100644
--- a/lib/src/utils/commands_extension.dart
+++ b/lib/src/utils/commands_extension.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2021 Famedly GmbH
diff --git a/lib/src/utils/crypto/crypto.dart b/lib/src/utils/crypto/crypto.dart
index fc4d1c97..7bbddf80 100644
--- a/lib/src/utils/crypto/crypto.dart
+++ b/lib/src/utils/crypto/crypto.dart
@@ -1,3 +1,21 @@
+/*
+ *   Famedly Matrix SDK
+ *   Copyright (C) 2019, 2020, 2021 Famedly GmbH
+ *
+ *   This program is free software: you can redistribute it and/or modify
+ *   it under the terms of the GNU Affero General Public License as
+ *   published by the Free Software Foundation, either version 3 of the
+ *   License, or (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ *   GNU Affero General Public License for more details.
+ *
+ *   You should have received a copy of the GNU Affero General Public License
+ *   along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
 export 'native.dart' if (dart.library.js) 'js.dart';
 
 import 'dart:typed_data';
diff --git a/lib/src/utils/crypto/encrypted_file.dart b/lib/src/utils/crypto/encrypted_file.dart
index 82528a79..847bf616 100644
--- a/lib/src/utils/crypto/encrypted_file.dart
+++ b/lib/src/utils/crypto/encrypted_file.dart
@@ -1,3 +1,21 @@
+// @dart=2.9
+/*
+ *   Famedly Matrix SDK
+ *   Copyright (C) 2019, 2020, 2021 Famedly GmbH
+ *
+ *   This program is free software: you can redistribute it and/or modify
+ *   it under the terms of the GNU Affero General Public License as
+ *   published by the Free Software Foundation, either version 3 of the
+ *   License, or (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ *   GNU Affero General Public License for more details.
+ *
+ *   You should have received a copy of the GNU Affero General Public License
+ *   along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 import 'dart:typed_data';
 import 'dart:convert';
 
diff --git a/lib/src/utils/crypto/ffi.dart b/lib/src/utils/crypto/ffi.dart
index 7b6a9d1f..0cb79266 100644
--- a/lib/src/utils/crypto/ffi.dart
+++ b/lib/src/utils/crypto/ffi.dart
@@ -1,3 +1,20 @@
+/*
+ *   Famedly Matrix SDK
+ *   Copyright (C) 2019, 2020, 2021 Famedly GmbH
+ *
+ *   This program is free software: you can redistribute it and/or modify
+ *   it under the terms of the GNU Affero General Public License as
+ *   published by the Free Software Foundation, either version 3 of the
+ *   License, or (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ *   GNU Affero General Public License for more details.
+ *
+ *   You should have received a copy of the GNU Affero General Public License
+ *   along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 import 'dart:ffi';
 import 'dart:io';
 
diff --git a/lib/src/utils/crypto/js.dart b/lib/src/utils/crypto/js.dart
index b889720a..56099614 100644
--- a/lib/src/utils/crypto/js.dart
+++ b/lib/src/utils/crypto/js.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 // Copyright (c) 2020 Famedly GmbH
 // SPDX-License-Identifier: AGPL-3.0-or-later
 
diff --git a/lib/src/utils/crypto/subtle.dart b/lib/src/utils/crypto/subtle.dart
index 7654b71d..6216c639 100644
--- a/lib/src/utils/crypto/subtle.dart
+++ b/lib/src/utils/crypto/subtle.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 // Copyright (c) 2020 Famedly GmbH
 // SPDX-License-Identifier: AGPL-3.0-or-later
 
diff --git a/lib/src/utils/device_keys_list.dart b/lib/src/utils/device_keys_list.dart
index d0adeda9..1dd67f7c 100644
--- a/lib/src/utils/device_keys_list.dart
+++ b/lib/src/utils/device_keys_list.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2020, 2021 Famedly GmbH
diff --git a/lib/src/utils/event_localizations.dart b/lib/src/utils/event_localizations.dart
index a6e0eeed..b5cd7a1f 100644
--- a/lib/src/utils/event_localizations.dart
+++ b/lib/src/utils/event_localizations.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2019, 2020, 2021 Famedly GmbH
diff --git a/lib/src/utils/event_update.dart b/lib/src/utils/event_update.dart
index 0667b35e..67af4e13 100644
--- a/lib/src/utils/event_update.dart
+++ b/lib/src/utils/event_update.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2019, 2020, 2021 Famedly GmbH
diff --git a/lib/src/utils/html_to_text.dart b/lib/src/utils/html_to_text.dart
index e2f4e702..6bd0b1c6 100644
--- a/lib/src/utils/html_to_text.dart
+++ b/lib/src/utils/html_to_text.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2021 Famedly GmbH
diff --git a/lib/src/utils/http_timeout.dart b/lib/src/utils/http_timeout.dart
index 9ebf4bce..108fceac 100644
--- a/lib/src/utils/http_timeout.dart
+++ b/lib/src/utils/http_timeout.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2021 Famedly GmbH
diff --git a/lib/src/utils/image_pack_extension.dart b/lib/src/utils/image_pack_extension.dart
index 05a5b0a0..19284c10 100644
--- a/lib/src/utils/image_pack_extension.dart
+++ b/lib/src/utils/image_pack_extension.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2020, 2021 Famedly GmbH
diff --git a/lib/src/utils/map_copy_extension.dart b/lib/src/utils/map_copy_extension.dart
index 520294f6..d57c625a 100644
--- a/lib/src/utils/map_copy_extension.dart
+++ b/lib/src/utils/map_copy_extension.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2020, 2021 Famedly GmbH
diff --git a/lib/src/utils/markdown.dart b/lib/src/utils/markdown.dart
index 8ffd7a0a..9d4c1441 100644
--- a/lib/src/utils/markdown.dart
+++ b/lib/src/utils/markdown.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2020, 2021 Famedly GmbH
diff --git a/lib/src/utils/marked_unread.dart b/lib/src/utils/marked_unread.dart
index b065335b..c235bbb3 100644
--- a/lib/src/utils/marked_unread.dart
+++ b/lib/src/utils/marked_unread.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2019, 2020, 2021 Famedly GmbH
diff --git a/lib/src/utils/matrix_file.dart b/lib/src/utils/matrix_file.dart
index f2b8b314..a4db480f 100644
--- a/lib/src/utils/matrix_file.dart
+++ b/lib/src/utils/matrix_file.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2020, 2021 Famedly GmbH
diff --git a/lib/src/utils/matrix_id_string_extension.dart b/lib/src/utils/matrix_id_string_extension.dart
index ede1bdf1..a92028a8 100644
--- a/lib/src/utils/matrix_id_string_extension.dart
+++ b/lib/src/utils/matrix_id_string_extension.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2020, 2021 Famedly GmbH
diff --git a/lib/src/utils/matrix_localizations.dart b/lib/src/utils/matrix_localizations.dart
index 4c96db66..69cb6e07 100644
--- a/lib/src/utils/matrix_localizations.dart
+++ b/lib/src/utils/matrix_localizations.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2020, 2021 Famedly GmbH
diff --git a/lib/src/utils/multilock.dart b/lib/src/utils/multilock.dart
index 30eb5890..cc2973b8 100644
--- a/lib/src/utils/multilock.dart
+++ b/lib/src/utils/multilock.dart
@@ -1,3 +1,21 @@
+// @dart=2.9
+/*
+ *   Famedly Matrix SDK
+ *   Copyright (C) 2019, 2020, 2021 Famedly GmbH
+ *
+ *   This program is free software: you can redistribute it and/or modify
+ *   it under the terms of the GNU Affero General Public License as
+ *   published by the Free Software Foundation, either version 3 of the
+ *   License, or (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ *   GNU Affero General Public License for more details.
+ *
+ *   You should have received a copy of the GNU Affero General Public License
+ *   along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 import 'dart:async';
 
 /// Lock management class. It allows to lock and unlock multiple keys at once. The keys have
diff --git a/lib/src/utils/receipt.dart b/lib/src/utils/receipt.dart
index 60bc4711..aab82f0b 100644
--- a/lib/src/utils/receipt.dart
+++ b/lib/src/utils/receipt.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2020, 2021 Famedly GmbH
diff --git a/lib/src/utils/room_update.dart b/lib/src/utils/room_update.dart
index 47d8e0d1..6a8db981 100644
--- a/lib/src/utils/room_update.dart
+++ b/lib/src/utils/room_update.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2019, 2020, 2021 Famedly GmbH
diff --git a/lib/src/utils/run_in_root.dart b/lib/src/utils/run_in_root.dart
index 1fe8dacc..99d59836 100644
--- a/lib/src/utils/run_in_root.dart
+++ b/lib/src/utils/run_in_root.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2020, 2021 Famedly GmbH
diff --git a/lib/src/utils/space_child.dart b/lib/src/utils/space_child.dart
index 01905ecc..210522ee 100644
--- a/lib/src/utils/space_child.dart
+++ b/lib/src/utils/space_child.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2019, 2020, 2021 Famedly GmbH
diff --git a/lib/src/utils/sync_update_extension.dart b/lib/src/utils/sync_update_extension.dart
index 64ecfac8..e0839aac 100644
--- a/lib/src/utils/sync_update_extension.dart
+++ b/lib/src/utils/sync_update_extension.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2020, 2021 Famedly GmbH
diff --git a/lib/src/utils/to_device_event.dart b/lib/src/utils/to_device_event.dart
index 0580374b..d6028312 100644
--- a/lib/src/utils/to_device_event.dart
+++ b/lib/src/utils/to_device_event.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2020, 2021 Famedly GmbH
diff --git a/lib/src/utils/uia_request.dart b/lib/src/utils/uia_request.dart
index e753d5a4..ed8f66e8 100644
--- a/lib/src/utils/uia_request.dart
+++ b/lib/src/utils/uia_request.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2020, 2021 Famedly GmbH
diff --git a/lib/src/utils/uri_extension.dart b/lib/src/utils/uri_extension.dart
index 93a4f0c3..e7b151a4 100644
--- a/lib/src/utils/uri_extension.dart
+++ b/lib/src/utils/uri_extension.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2019, 2020, 2021 Famedly GmbH
diff --git a/pubspec.yaml b/pubspec.yaml
index d9a2f40f..0ccd5ea3 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -4,7 +4,7 @@ version: 0.2.1
 homepage: https://famedly.com
 
 environment:
-  sdk: ">=2.7.0 <3.0.0"
+  sdk: ">=2.12.0 <3.0.0"
 
 dependencies:
   http: ^0.13.0
diff --git a/test/canonical_json_test.dart b/test/canonical_json_test.dart
index 8787dce0..89bd50d9 100644
--- a/test/canonical_json_test.dart
+++ b/test/canonical_json_test.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2019, 2020 Famedly GmbH
diff --git a/test/client_test.dart b/test/client_test.dart
index ff129ddc..88e14d7a 100644
--- a/test/client_test.dart
+++ b/test/client_test.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2019, 2020 Famedly GmbH
diff --git a/test/commands_test.dart b/test/commands_test.dart
index a5997a29..d01180d8 100644
--- a/test/commands_test.dart
+++ b/test/commands_test.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2021 Famedly GmbH
diff --git a/test/database_api_test.dart b/test/database_api_test.dart
index 7c18f415..94fe12c0 100644
--- a/test/database_api_test.dart
+++ b/test/database_api_test.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2019, 2020 Famedly GmbH
diff --git a/test/device_keys_list_test.dart b/test/device_keys_list_test.dart
index d6583bf3..a1aa9ad7 100644
--- a/test/device_keys_list_test.dart
+++ b/test/device_keys_list_test.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2019, 2020 Famedly GmbH
diff --git a/test/encryption/bootstrap_test.dart b/test/encryption/bootstrap_test.dart
index b62f64fc..7cd9d1aa 100644
--- a/test/encryption/bootstrap_test.dart
+++ b/test/encryption/bootstrap_test.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2020 Famedly GmbH
diff --git a/test/encryption/cross_signing_test.dart b/test/encryption/cross_signing_test.dart
index e6ec4f80..2288c091 100644
--- a/test/encryption/cross_signing_test.dart
+++ b/test/encryption/cross_signing_test.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2020 Famedly GmbH
diff --git a/test/encryption/encrypt_decrypt_room_message_test.dart b/test/encryption/encrypt_decrypt_room_message_test.dart
index 357a0352..24d1fb2d 100644
--- a/test/encryption/encrypt_decrypt_room_message_test.dart
+++ b/test/encryption/encrypt_decrypt_room_message_test.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2020 Famedly GmbH
diff --git a/test/encryption/encrypt_decrypt_to_device_test.dart b/test/encryption/encrypt_decrypt_to_device_test.dart
index 9555440f..47fec8df 100644
--- a/test/encryption/encrypt_decrypt_to_device_test.dart
+++ b/test/encryption/encrypt_decrypt_to_device_test.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2020 Famedly GmbH
diff --git a/test/encryption/key_manager_test.dart b/test/encryption/key_manager_test.dart
index 73a26c56..70448aa9 100644
--- a/test/encryption/key_manager_test.dart
+++ b/test/encryption/key_manager_test.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2020 Famedly GmbH
diff --git a/test/encryption/key_request_test.dart b/test/encryption/key_request_test.dart
index b2a5e575..ed748498 100644
--- a/test/encryption/key_request_test.dart
+++ b/test/encryption/key_request_test.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2020 Famedly GmbH
diff --git a/test/encryption/key_verification_test.dart b/test/encryption/key_verification_test.dart
index 6feebd5f..b4d7e242 100644
--- a/test/encryption/key_verification_test.dart
+++ b/test/encryption/key_verification_test.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2020 Famedly GmbH
diff --git a/test/encryption/olm_manager_test.dart b/test/encryption/olm_manager_test.dart
index 9d4ad2a3..858f5914 100644
--- a/test/encryption/olm_manager_test.dart
+++ b/test/encryption/olm_manager_test.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2020, 2021 Famedly GmbH
diff --git a/test/encryption/online_key_backup_test.dart b/test/encryption/online_key_backup_test.dart
index 1210ea12..12f33995 100644
--- a/test/encryption/online_key_backup_test.dart
+++ b/test/encryption/online_key_backup_test.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2020 Famedly GmbH
diff --git a/test/encryption/ssss_test.dart b/test/encryption/ssss_test.dart
index 7586329d..4189e1f8 100644
--- a/test/encryption/ssss_test.dart
+++ b/test/encryption/ssss_test.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2020 Famedly GmbH
diff --git a/test/event_test.dart b/test/event_test.dart
index 725aaf62..73160904 100644
--- a/test/event_test.dart
+++ b/test/event_test.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2019, 2020 Famedly GmbH
diff --git a/test/fake_client.dart b/test/fake_client.dart
index 0a13c708..2563dcaa 100644
--- a/test/fake_client.dart
+++ b/test/fake_client.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2020 Famedly GmbH
diff --git a/test/fake_database.dart b/test/fake_database.dart
index 182dede9..cd9f6714 100644
--- a/test/fake_database.dart
+++ b/test/fake_database.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2019, 2020 Famedly GmbH
diff --git a/test/fake_matrix_api.dart b/test/fake_matrix_api.dart
index 67f352d0..6776fc8c 100644
--- a/test/fake_matrix_api.dart
+++ b/test/fake_matrix_api.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2019, 2020 Famedly GmbH
diff --git a/test/fake_matrix_localizations.dart b/test/fake_matrix_localizations.dart
index cbc2c157..b9ca8aa7 100644
--- a/test/fake_matrix_localizations.dart
+++ b/test/fake_matrix_localizations.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2019, 2020 Famedly GmbH
diff --git a/test/html_to_text_test.dart b/test/html_to_text_test.dart
index 63803aac..480368cf 100644
--- a/test/html_to_text_test.dart
+++ b/test/html_to_text_test.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2021 Famedly GmbH
diff --git a/test/image_pack_test.dart b/test/image_pack_test.dart
index 3d76e549..5ed3282c 100644
--- a/test/image_pack_test.dart
+++ b/test/image_pack_test.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2021 Famedly GmbH
diff --git a/test/markdown_test.dart b/test/markdown_test.dart
index c9e323a8..0770d6ee 100644
--- a/test/markdown_test.dart
+++ b/test/markdown_test.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2019, 2020 Famedly GmbH
diff --git a/test/matrix_api/map_copy_extension_test.dart b/test/matrix_api/map_copy_extension_test.dart
index e7027952..6ecb62c2 100644
--- a/test/matrix_api/map_copy_extension_test.dart
+++ b/test/matrix_api/map_copy_extension_test.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2020 Famedly GmbH
diff --git a/test/matrix_api/try_get_map_extension_test.dart b/test/matrix_api/try_get_map_extension_test.dart
index 886700e3..f7adccb3 100644
--- a/test/matrix_api/try_get_map_extension_test.dart
+++ b/test/matrix_api/try_get_map_extension_test.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2020 Famedly GmbH
diff --git a/test/matrix_database_test.dart b/test/matrix_database_test.dart
index f812b61a..852a1c14 100644
--- a/test/matrix_database_test.dart
+++ b/test/matrix_database_test.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2020 Famedly GmbH
diff --git a/test/matrix_default_localizations.dart b/test/matrix_default_localizations.dart
index 3ab973ff..d8389542 100644
--- a/test/matrix_default_localizations.dart
+++ b/test/matrix_default_localizations.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2019, 2020 Famedly GmbH
diff --git a/test/matrix_exception_test.dart b/test/matrix_exception_test.dart
index 79134e7a..c49fd4d7 100644
--- a/test/matrix_exception_test.dart
+++ b/test/matrix_exception_test.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2019, 2020 Famedly GmbH
diff --git a/test/matrix_file_test.dart b/test/matrix_file_test.dart
index 6b509461..dd0e6cca 100644
--- a/test/matrix_file_test.dart
+++ b/test/matrix_file_test.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2019, 2020 Famedly GmbH
diff --git a/test/matrix_id_string_extension_test.dart b/test/matrix_id_string_extension_test.dart
index 05f93b57..409a5f54 100644
--- a/test/matrix_id_string_extension_test.dart
+++ b/test/matrix_id_string_extension_test.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2019, 2020 Famedly GmbH
diff --git a/test/matrix_localizations_test.dart b/test/matrix_localizations_test.dart
index 6f92b372..f9684e29 100644
--- a/test/matrix_localizations_test.dart
+++ b/test/matrix_localizations_test.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2019, 2020 Famedly GmbH
diff --git a/test/multilock_test.dart b/test/multilock_test.dart
index 292b1e4e..9f7da34b 100644
--- a/test/multilock_test.dart
+++ b/test/multilock_test.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2021 Famedly GmbH
diff --git a/test/mxc_uri_extension_test.dart b/test/mxc_uri_extension_test.dart
index b4d505e7..b6319c03 100644
--- a/test/mxc_uri_extension_test.dart
+++ b/test/mxc_uri_extension_test.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2019, 2020 Famedly GmbH
diff --git a/test/room_test.dart b/test/room_test.dart
index 8623b34a..c3956cb3 100644
--- a/test/room_test.dart
+++ b/test/room_test.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2019, 2020 Famedly GmbH
diff --git a/test/sync_filter_test.dart b/test/sync_filter_test.dart
index e1a8f92e..8a76b805 100644
--- a/test/sync_filter_test.dart
+++ b/test/sync_filter_test.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2020 Famedly GmbH
diff --git a/test/timeline_test.dart b/test/timeline_test.dart
index cd6a8882..a39d5df6 100644
--- a/test/timeline_test.dart
+++ b/test/timeline_test.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2019, 2020 Famedly GmbH
diff --git a/test/uia_test.dart b/test/uia_test.dart
index 11140ff9..aa262890 100644
--- a/test/uia_test.dart
+++ b/test/uia_test.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2020 Famedly GmbH
diff --git a/test/user_test.dart b/test/user_test.dart
index 10bb17a6..2e32c01e 100644
--- a/test/user_test.dart
+++ b/test/user_test.dart
@@ -1,3 +1,4 @@
+// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2019, 2020 Famedly GmbH
diff --git a/test_driver/matrixsdk_test.dart b/test_driver/matrixsdk_test.dart
index 67d1b485..1bab3ab5 100644
--- a/test_driver/matrixsdk_test.dart
+++ b/test_driver/matrixsdk_test.dart
@@ -1,3 +1,21 @@
+// @dart=2.9
+/*
+ *   Famedly Matrix SDK
+ *   Copyright (C) 2019, 2020, 2021 Famedly GmbH
+ *
+ *   This program is free software: you can redistribute it and/or modify
+ *   it under the terms of the GNU Affero General Public License as
+ *   published by the Free Software Foundation, either version 3 of the
+ *   License, or (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ *   GNU Affero General Public License for more details.
+ *
+ *   You should have received a copy of the GNU Affero General Public License
+ *   along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 import 'package:matrix/matrix.dart';
 import '../test/fake_database.dart';
 import 'test_config.dart';