diff --git a/lib/matrix_api_lite.dart b/lib/matrix_api_lite.dart
index d90c0a1b..f2ac3ec3 100644
--- a/lib/matrix_api_lite.dart
+++ b/lib/matrix_api_lite.dart
@@ -20,6 +20,7 @@ library matrix_api_lite;
 
 export 'src/matrix_api.dart';
 export 'src/utils/logs.dart';
+export 'src/utils/map_copy_extension.dart';
 export 'src/utils/try_get_map_extension.dart';
 export 'src/model/algorithm_types.dart';
 export 'src/model/basic_event.dart';
diff --git a/lib/src/model/auth/authentication_password.dart b/lib/src/model/auth/authentication_password.dart
index fe28d1c8..6ae4df3f 100644
--- a/lib/src/model/auth/authentication_password.dart
+++ b/lib/src/model/auth/authentication_password.dart
@@ -17,6 +17,7 @@
  */
 
 import 'authentication_user_identifier.dart';
+
 import 'authentication_data.dart';
 import 'authentication_identifier.dart';
 import 'authentication_phone_identifier.dart';
diff --git a/lib/src/model/basic_event.dart b/lib/src/model/basic_event.dart
index 095b2b21..7a91f559 100644
--- a/lib/src/model/basic_event.dart
+++ b/lib/src/model/basic_event.dart
@@ -16,6 +16,8 @@
  *   along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
 
+import '../utils/map_copy_extension.dart';
+
 class BasicEvent {
   String type;
   Map<String, dynamic> content;
@@ -27,7 +29,7 @@ class BasicEvent {
 
   BasicEvent.fromJson(Map<String, dynamic> json) {
     type = json['type'];
-    content = Map<String, dynamic>.from(json['content']);
+    content = (json['content'] as Map<String, dynamic>).copy();
   }
   Map<String, dynamic> toJson() {
     final data = <String, dynamic>{};
diff --git a/lib/src/model/keys_query_response.dart b/lib/src/model/keys_query_response.dart
index b368b4f1..ed02e87d 100644
--- a/lib/src/model/keys_query_response.dart
+++ b/lib/src/model/keys_query_response.dart
@@ -17,6 +17,7 @@
  */
 
 import 'matrix_keys.dart';
+import '../utils/map_copy_extension.dart';
 
 class KeysQueryResponse {
   Map<String, dynamic> failures;
@@ -26,9 +27,7 @@ class KeysQueryResponse {
   Map<String, MatrixCrossSigningKey> userSigningKeys;
 
   KeysQueryResponse.fromJson(Map<String, dynamic> json) {
-    failures = json['failures'] != null
-        ? Map<String, dynamic>.from(json['failures'])
-        : null;
+    failures = (json['failures'] as Map<String, dynamic>)?.copy();
     deviceKeys = json['device_keys'] != null
         ? (json['device_keys'] as Map).map(
             (k, v) => MapEntry(
diff --git a/lib/src/model/matrix_event.dart b/lib/src/model/matrix_event.dart
index 2f5f35f0..83fe7596 100644
--- a/lib/src/model/matrix_event.dart
+++ b/lib/src/model/matrix_event.dart
@@ -17,6 +17,7 @@
  */
 
 import 'stripped_state_event.dart';
+import '../utils/map_copy_extension.dart';
 
 class MatrixEvent extends StrippedStateEvent {
   String eventId;
@@ -38,12 +39,8 @@ class MatrixEvent extends StrippedStateEvent {
     roomId = json['room_id'];
     originServerTs =
         DateTime.fromMillisecondsSinceEpoch(json['origin_server_ts']);
-    unsigned = json['unsigned'] != null
-        ? Map<String, dynamic>.from(json['unsigned'])
-        : null;
-    prevContent = json['prev_content'] != null
-        ? Map<String, dynamic>.from(json['prev_content'])
-        : null;
+    unsigned = (json['unsigned'] as Map<String, dynamic>)?.copy();
+    prevContent = (json['prev_content'] as Map<String, dynamic>)?.copy();
     redacts = json['redacts'];
   }
 
diff --git a/lib/src/model/matrix_keys.dart b/lib/src/model/matrix_keys.dart
index c0f00386..317ef390 100644
--- a/lib/src/model/matrix_keys.dart
+++ b/lib/src/model/matrix_keys.dart
@@ -16,6 +16,8 @@
  *   along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
 
+import '../utils/map_copy_extension.dart';
+
 class MatrixSignableKey {
   String userId;
   String identifier;
@@ -33,13 +35,12 @@ class MatrixSignableKey {
     _json = json;
     userId = json['user_id'];
     keys = Map<String, String>.from(json['keys']);
+    // we need to manually copy to ensure that our map is Map<String, Map<String, String>>
     signatures = json['signatures'] is Map
         ? Map<String, Map<String, String>>.from((json['signatures'] as Map)
             .map((k, v) => MapEntry(k, Map<String, String>.from(v))))
         : null;
-    unsigned = json['unsigned'] is Map
-        ? Map<String, dynamic>.from(json['unsigned'])
-        : null;
+    unsigned = (json['unsigned'] as Map<String, dynamic>)?.copy();
   }
 
   Map<String, dynamic> toJson() {
diff --git a/lib/src/model/one_time_keys_claim_response.dart b/lib/src/model/one_time_keys_claim_response.dart
index 7834211c..7607892b 100644
--- a/lib/src/model/one_time_keys_claim_response.dart
+++ b/lib/src/model/one_time_keys_claim_response.dart
@@ -16,13 +16,17 @@
  *   along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
 
+import '../utils/map_copy_extension.dart';
+
 class OneTimeKeysClaimResponse {
   Map<String, dynamic> failures;
   Map<String, Map<String, dynamic>> oneTimeKeys;
 
   OneTimeKeysClaimResponse.fromJson(Map<String, dynamic> json) {
-    failures = Map<String, dynamic>.from(json['failures'] ?? {});
-    oneTimeKeys = Map<String, Map<String, dynamic>>.from(json['one_time_keys']);
+    failures = (json['failures'] as Map<String, dynamic>)?.copy() ?? {};
+    // We still need a Map<...>.from(...) to ensure all second-level entries are also maps
+    oneTimeKeys = Map<String, Map<String, dynamic>>.from(
+        (json['one_time_keys'] as Map<String, dynamic>).copy());
   }
 
   Map<String, dynamic> toJson() {
diff --git a/lib/src/model/room_keys_info.dart b/lib/src/model/room_keys_info.dart
index 2ac7ac3c..037b20e1 100644
--- a/lib/src/model/room_keys_info.dart
+++ b/lib/src/model/room_keys_info.dart
@@ -16,7 +16,7 @@
  *   along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
 
-import 'algorithm_types.dart';
+import '../../matrix_api_lite.dart';
 
 enum RoomKeysAlgorithmType { v1Curve25519AesSha2 }
 
diff --git a/lib/src/model/server_capabilities.dart b/lib/src/model/server_capabilities.dart
index 0e449e9d..0ae7c1ee 100644
--- a/lib/src/model/server_capabilities.dart
+++ b/lib/src/model/server_capabilities.dart
@@ -16,6 +16,8 @@
  *   along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
 
+import '../utils/map_copy_extension.dart';
+
 enum RoomVersionStability { stable, unstable }
 
 class ServerCapabilities {
@@ -30,7 +32,7 @@ class ServerCapabilities {
     mRoomVersions = json['m.room_versions'] != null
         ? MRoomVersions.fromJson(json['m.room_versions'])
         : null;
-    customCapabilities = Map<String, dynamic>.from(json);
+    customCapabilities = json.copy();
     customCapabilities.remove('m.change_password');
     customCapabilities.remove('m.room_versions');
   }
diff --git a/lib/src/model/third_party_identifier.dart b/lib/src/model/third_party_identifier.dart
index 14fe31d8..25d5b469 100644
--- a/lib/src/model/third_party_identifier.dart
+++ b/lib/src/model/third_party_identifier.dart
@@ -16,7 +16,7 @@
  *   along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
 
-import '../../matrix_api_lite.dart';
+import '../matrix_api.dart';
 
 class ThirdPartyIdentifier {
   ThirdPartyIdentifierMedium medium;
diff --git a/lib/src/model/third_party_location.dart b/lib/src/model/third_party_location.dart
index 68083805..39546099 100644
--- a/lib/src/model/third_party_location.dart
+++ b/lib/src/model/third_party_location.dart
@@ -16,6 +16,8 @@
  *   along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
 
+import '../utils/map_copy_extension.dart';
+
 class ThirdPartyLocation {
   String alias;
   String protocol;
@@ -24,7 +26,7 @@ class ThirdPartyLocation {
   ThirdPartyLocation.fromJson(Map<String, dynamic> json) {
     alias = json['alias'];
     protocol = json['protocol'];
-    fields = Map<String, dynamic>.from(json['fields']);
+    fields = (json['fields'] as Map<String, dynamic>).copy();
   }
 
   Map<String, dynamic> toJson() {
diff --git a/lib/src/model/third_party_user.dart b/lib/src/model/third_party_user.dart
index fd84f907..e19818e8 100644
--- a/lib/src/model/third_party_user.dart
+++ b/lib/src/model/third_party_user.dart
@@ -16,6 +16,8 @@
  *   along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
 
+import '../utils/map_copy_extension.dart';
+
 class ThirdPartyUser {
   String userId;
   String protocol;
@@ -24,7 +26,7 @@ class ThirdPartyUser {
   ThirdPartyUser.fromJson(Map<String, dynamic> json) {
     userId = json['userid'];
     protocol = json['protocol'];
-    fields = Map<String, dynamic>.from(json['fields']);
+    fields = (json['fields'] as Map<String, dynamic>).copy();
   }
 
   Map<String, dynamic> toJson() {
diff --git a/lib/src/utils/map_copy_extension.dart b/lib/src/utils/map_copy_extension.dart
new file mode 100644
index 00000000..84ddc272
--- /dev/null
+++ b/lib/src/utils/map_copy_extension.dart
@@ -0,0 +1,33 @@
+/*
+ *   Famedly Matrix SDK
+ *   Copyright (C) 2020 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/>.
+ */
+
+extension MapCopyExtension on Map<String, dynamic> {
+  /// Deep-copies a given json map
+  Map<String, dynamic> copy() {
+    final copy = Map<String, dynamic>.from(this);
+    for (final entry in copy.entries) {
+      if (entry.value is Map<String, dynamic>) {
+        copy[entry.key] = (entry.value as Map<String, dynamic>).copy();
+      }
+      if (entry.value is List) {
+        copy[entry.key] = List.from(entry.value);
+      }
+    }
+    return copy;
+  }
+}