diff --git a/lib/src/utils/matrix_id_string_extension.dart b/lib/src/utils/matrix_id_string_extension.dart
index 296a780..685e12e 100644
--- a/lib/src/utils/matrix_id_string_extension.dart
+++ b/lib/src/utils/matrix_id_string_extension.dart
@@ -9,8 +9,14 @@ extension MatrixIdExtension on String {
     if (!VALID_SIGILS.contains(substring(0, 1))) {
       return false;
     }
+    // event IDs do not have to have a domain
+    if (substring(0, 1) == '\$') {
+      return true;
+    }
+    // all other matrix IDs have to have a domain
     final parts = substring(1).split(':');
-    if (parts.length != 2 || parts[0].isEmpty || parts[1].isEmpty) {
+    // the localpart can be an empty string, e.g. for aliases
+    if (parts.length != 2 || parts[1].isEmpty) {
       return false;
     }
     return true;
diff --git a/test/matrix_id_string_extension_test.dart b/test/matrix_id_string_extension_test.dart
index 5cacdd8..0ee37c3 100644
--- a/test/matrix_id_string_extension_test.dart
+++ b/test/matrix_id_string_extension_test.dart
@@ -29,9 +29,10 @@ void main() {
       expect('!test:example.com'.isValidMatrixId, true);
       expect('+test:example.com'.isValidMatrixId, true);
       expect('\$test:example.com'.isValidMatrixId, true);
+      expect('\$testevent'.isValidMatrixId, true);
       expect('test:example.com'.isValidMatrixId, false);
       expect('@testexample.com'.isValidMatrixId, false);
-      expect('@:example.com'.isValidMatrixId, false);
+      expect('@:example.com'.isValidMatrixId, true);
       expect('@test:'.isValidMatrixId, false);
       expect(mxId.sigil, '@');
       expect('#test:example.com'.sigil, '#');