diff --git a/lexers/embedded/dart.xml b/lexers/embedded/dart.xml
index 9fef38d..f1b454f 100644
--- a/lexers/embedded/dart.xml
+++ b/lexers/embedded/dart.xml
@@ -97,7 +97,7 @@
       <rule pattern="\b(assert|break|case|catch|continue|default|do|else|finally|for|if|in|is|new|return|super|switch|this|throw|try|while)\b">
         <token type="Keyword"/>
       </rule>
-      <rule pattern="\b(abstract|async|await|const|extends|factory|final|get|implements|native|operator|set|static|sync|typedef|var|with|yield)\b">
+      <rule pattern="\b(abstract|async|await|const|extends|factory|final|get|implements|native|operator|required|set|static|sync|typedef|var|with|yield)\b">
         <token type="KeywordDeclaration"/>
       </rule>
       <rule pattern="\b(bool|double|dynamic|int|num|Object|String|void)\b">
diff --git a/lexers/testdata/dart.actual b/lexers/testdata/dart.actual
index b3f4bd6..a7f0670 100644
--- a/lexers/testdata/dart.actual
+++ b/lexers/testdata/dart.actual
@@ -3,8 +3,8 @@ import 'dart:html';
 import 'dart:math' show Random;
 
 // We changed 5 lines of code to make this sample nicer on
-// the web (so that the execution waits for animation frame, 
-// the number gets updated in the DOM, and the program ends 
+// the web (so that the execution waits for animation frame,
+// the number gets updated in the DOM, and the program ends
 // after 500 iterations).
 
 main() async {
@@ -39,12 +39,12 @@ Stream<double> computePi({int batch: 100000}) async* {
 Iterable<Point> generateRandom([int seed]) sync* {
   final random = new Random(seed);
   while (true) {
-    yield new Point(random.nextDouble(), random.nextDouble());
+    yield new Point(x: random.nextDouble(), y: random.nextDouble());
   }
 }
 
 class Point {
   final double x, y;
-  const Point(this.x, this.y);
+  const Point({required this.x, required this.y});
   bool get isInsideUnitCircle => x * x + y * y <= 1;
 }
\ No newline at end of file
diff --git a/lexers/testdata/dart.expected b/lexers/testdata/dart.expected
index 36b0a81..9e77b74 100644
--- a/lexers/testdata/dart.expected
+++ b/lexers/testdata/dart.expected
@@ -18,7 +18,7 @@
   {"type":"Name","value":"Random"},
   {"type":"Punctuation","value":";"},
   {"type":"Text","value":"\n\n"},
-  {"type":"CommentSingle","value":"// We changed 5 lines of code to make this sample nicer on\n// the web (so that the execution waits for animation frame, \n// the number gets updated in the DOM, and the program ends \n// after 500 iterations).\n"},
+  {"type":"CommentSingle","value":"// We changed 5 lines of code to make this sample nicer on\n// the web (so that the execution waits for animation frame,\n// the number gets updated in the DOM, and the program ends\n// after 500 iterations).\n"},
   {"type":"Text","value":"\n"},
   {"type":"Name","value":"main"},
   {"type":"Punctuation","value":"()"},
@@ -270,11 +270,15 @@
   {"type":"Text","value":" "},
   {"type":"Name","value":"Point"},
   {"type":"Punctuation","value":"("},
+  {"type":"NameLabel","value":"x:"},
+  {"type":"Text","value":" "},
   {"type":"Name","value":"random"},
   {"type":"Punctuation","value":"."},
   {"type":"Name","value":"nextDouble"},
   {"type":"Punctuation","value":"(),"},
   {"type":"Text","value":" "},
+  {"type":"NameLabel","value":"y:"},
+  {"type":"Text","value":" "},
   {"type":"Name","value":"random"},
   {"type":"Punctuation","value":"."},
   {"type":"Name","value":"nextDouble"},
@@ -303,16 +307,20 @@
   {"type":"KeywordDeclaration","value":"const"},
   {"type":"Text","value":" "},
   {"type":"Name","value":"Point"},
-  {"type":"Punctuation","value":"("},
+  {"type":"Punctuation","value":"({"},
+  {"type":"KeywordDeclaration","value":"required"},
+  {"type":"Text","value":" "},
   {"type":"Keyword","value":"this"},
   {"type":"Punctuation","value":"."},
   {"type":"Name","value":"x"},
   {"type":"Punctuation","value":","},
   {"type":"Text","value":" "},
+  {"type":"KeywordDeclaration","value":"required"},
+  {"type":"Text","value":" "},
   {"type":"Keyword","value":"this"},
   {"type":"Punctuation","value":"."},
   {"type":"Name","value":"y"},
-  {"type":"Punctuation","value":");"},
+  {"type":"Punctuation","value":"});"},
   {"type":"Text","value":"\n  "},
   {"type":"KeywordType","value":"bool"},
   {"type":"Text","value":" "},