diff --git a/lib/matrix_api/model/matrix_event.dart b/lib/matrix_api/model/matrix_event.dart
index 0a20bf5..e70f8b5 100644
--- a/lib/matrix_api/model/matrix_event.dart
+++ b/lib/matrix_api/model/matrix_event.dart
@@ -41,10 +41,9 @@ class MatrixEvent extends StrippedStateEvent {
     unsigned = json['unsigned'] != null
         ? Map<String, dynamic>.from(json['unsigned'])
         : null;
-    prevContent =
-        json.containsKey('prev_content') && json['prev_content'] != null
-            ? Map<String, dynamic>.from(json['prev_content'])
-            : null;
+    prevContent = json['prev_content'] != null
+        ? Map<String, dynamic>.from(json['prev_content'])
+        : null;
     redacts = json['redacts'];
   }
 
diff --git a/lib/src/event.dart b/lib/src/event.dart
index 154f090..47ca3d0 100644
--- a/lib/src/event.dart
+++ b/lib/src/event.dart
@@ -93,9 +93,7 @@ class Event extends MatrixEvent {
     // into the unsigned block
     this.prevContent = prevContent != null && prevContent.isNotEmpty
         ? prevContent
-        : (unsigned != null &&
-                unsigned.containsKey('prev_content') &&
-                unsigned['prev_content'] is Map
+        : (unsigned != null && unsigned['prev_content'] is Map
             ? unsigned['prev_content']
             : null);
     this.stateKey = stateKey;
@@ -483,10 +481,10 @@ class Event extends MatrixEvent {
         final targetName = stateKeyUser.calcDisplayname();
         // Has the membership changed?
         final newMembership = content['membership'] ?? '';
-        final oldMembership = unsigned.containsKey('prev_content') &&
-                unsigned['prev_content'] is Map<String, dynamic>
-            ? unsigned['prev_content']['membership'] ?? ''
-            : '';
+        final oldMembership =
+            unsigned != null && unsigned['prev_content'] is Map<String, dynamic>
+                ? unsigned['prev_content']['membership'] ?? ''
+                : '';
         if (newMembership != oldMembership) {
           if (oldMembership == 'invite' && newMembership == 'join') {
             text = i18n.acceptedTheInvitation(targetName);
@@ -521,13 +519,13 @@ class Event extends MatrixEvent {
           }
         } else if (newMembership == 'join') {
           final newAvatar = content['avatar_url'] ?? '';
-          final oldAvatar = unsigned.containsKey('prev_content') &&
+          final oldAvatar = unsigned != null &&
                   unsigned['prev_content'] is Map<String, dynamic>
               ? unsigned['prev_content']['avatar_url'] ?? ''
               : '';
 
           final newDisplayname = content['displayname'] ?? '';
-          final oldDisplayname = unsigned.containsKey('prev_content') &&
+          final oldDisplayname = unsigned != null &&
                   unsigned['prev_content'] is Map<String, dynamic>
               ? unsigned['prev_content']['displayname'] ?? ''
               : '';