diff --git a/pkg/front_end/lib/src/fasta/scanner.dart b/pkg/front_end/lib/src/fasta/scanner.dart
index a6e262a..f9f1741 100644
--- a/pkg/front_end/lib/src/fasta/scanner.dart
+++ b/pkg/front_end/lib/src/fasta/scanner.dart
@@ -8,7 +8,8 @@
 
 import '../scanner/token.dart' show Token;
 
-import 'scanner/abstract_scanner.dart' show ScannerConfiguration;
+import 'scanner/abstract_scanner.dart'
+    show LanguageVersionChanged, ScannerConfiguration;
 
 import 'scanner/string_scanner.dart' show StringScanner;
 
@@ -18,7 +19,8 @@
 
 import 'scanner/recover.dart' show defaultRecoveryStrategy;
 
-export 'scanner/abstract_scanner.dart' show ScannerConfiguration;
+export 'scanner/abstract_scanner.dart'
+    show LanguageVersionChanged, ScannerConfiguration;
 
 export 'scanner/token.dart'
     show
@@ -33,6 +35,8 @@
 export 'scanner/error_token.dart'
     show ErrorToken, buildUnexpectedCharacterToken;
 
+export 'scanner/token.dart' show LanguageVersionToken;
+
 export 'scanner/token_constants.dart' show EOF_TOKEN;
 
 export 'scanner/utf8_bytes_scanner.dart' show Utf8BytesScanner;
@@ -55,6 +59,9 @@
 
   List<int> get lineStarts;
 
+  /// Configure which tokens are produced.
+  set configuration(ScannerConfiguration config);
+
   Token tokenize();
 }
 
@@ -71,14 +78,17 @@
 /// Scan/tokenize the given UTF8 [bytes].
 /// If [recover] is null, then the [defaultRecoveryStrategy] is used.
 ScannerResult scan(List<int> bytes,
-    {bool includeComments: false,
-    ScannerConfiguration configuration,
+    {ScannerConfiguration configuration,
+    bool includeComments: false,
+    LanguageVersionChanged languageVersionChanged,
     Recover recover}) {
   if (bytes.last != 0) {
     throw new ArgumentError("[bytes]: the last byte must be null.");
   }
   Scanner scanner = new Utf8BytesScanner(bytes,
-      configuration: configuration, includeComments: includeComments);
+      configuration: configuration,
+      includeComments: includeComments,
+      languageVersionChanged: languageVersionChanged);
   return _tokenizeAndRecover(scanner, recover, bytes: bytes);
 }
 
@@ -87,11 +97,14 @@
 ScannerResult scanString(String source,
     {ScannerConfiguration configuration,
     bool includeComments: false,
+    LanguageVersionChanged languageVersionChanged,
     bool scanLazyAssignmentOperators: false,
     Recover recover}) {
   assert(source != null, 'source must not be null');
   StringScanner scanner = new StringScanner(source,
-      configuration: configuration, includeComments: includeComments);
+      configuration: configuration,
+      includeComments: includeComments,
+      languageVersionChanged: languageVersionChanged);
   return _tokenizeAndRecover(scanner, recover, source: source);
 }
 
diff --git a/pkg/front_end/lib/src/fasta/scanner/abstract_scanner.dart b/pkg/front_end/lib/src/fasta/scanner/abstract_scanner.dart
index fd29cd4..79ba63d 100644
--- a/pkg/front_end/lib/src/fasta/scanner/abstract_scanner.dart
+++ b/pkg/front_end/lib/src/fasta/scanner/abstract_scanner.dart
@@ -32,6 +32,9 @@
 
 import 'characters.dart';
 
+typedef void LanguageVersionChanged(
+    Scanner scanner, LanguageVersionToken languageVersion);
+
 abstract class AbstractScanner implements Scanner {
   /**
    * A flag indicating whether character sequences `&&=` and `||=`
@@ -43,6 +46,11 @@
 
   final bool includeComments;
 
+  /// Called when the scanner detects a language version comment
+  /// so that the listener can update the scanner configuration
+  /// based upon the specified language version.
+  final LanguageVersionChanged languageVersionChanged;
+
   /// Experimental flag for enabling scanning of `>>>`.
   /// See https://github.com/dart-lang/language/issues/61
   /// and https://github.com/dart-lang/language/issues/60
@@ -98,15 +106,14 @@
   final List<int> lineStarts;
 
   AbstractScanner(ScannerConfiguration config, this.includeComments,
+      this.languageVersionChanged,
       {int numberOfBytesHint})
       : lineStarts = new LineStarts(numberOfBytesHint) {
     this.tail = this.tokens;
     this.configuration = config;
   }
 
-  /**
-   * Configure which tokens are produced.
-   */
+  @override
   set configuration(ScannerConfiguration config) {
     if (config != null) {
       _enableNonNullable = config.enableNonNullable;
@@ -320,7 +327,7 @@
   }
 
   int bigHeaderSwitch(int next) {
-    if (languageVersion != null || !identical(next, $SLASH)) {
+    if (!identical(next, $SLASH)) {
       return bigSwitch(next);
     }
     beginToken();
@@ -970,7 +977,14 @@
     }
 
     languageVersion = createLanguageVersionToken(start, major, minor);
-    configuration = ScannerConfiguration.from(languageVersion);
+    if (languageVersionChanged != null) {
+      // TODO(danrubel): make this required and remove the languageVersion field
+      languageVersionChanged(this, languageVersion);
+    } else {
+      // TODO(danrubel): remove this hack and require listener to update
+      // the scanner's configuration.
+      configuration = ScannerConfiguration.classic;
+    }
     if (includeComments) {
       _appendToCommentStream(languageVersion);
     }
@@ -1528,12 +1542,6 @@
   static const classic = ScannerConfiguration();
   static const nonNullable = ScannerConfiguration(enableNonNullable: true);
 
-  /// Return the scanner configuration for the given language version.
-  static ScannerConfiguration from(LanguageVersionToken languageVersion) {
-    // TODO(danrubel): update this to return config for new releases
-    return classic;
-  }
-
   /// Experimental flag for enabling scanning of NNBD tokens
   /// such as 'required' and 'late'
   final bool enableNonNullable;
diff --git a/pkg/front_end/lib/src/fasta/scanner/array_based_scanner.dart b/pkg/front_end/lib/src/fasta/scanner/array_based_scanner.dart
index 66e7e39..22df483 100644
--- a/pkg/front_end/lib/src/fasta/scanner/array_based_scanner.dart
+++ b/pkg/front_end/lib/src/fasta/scanner/array_based_scanner.dart
@@ -21,7 +21,11 @@
 import 'characters.dart' show $LF, $STX;
 
 import 'abstract_scanner.dart'
-    show AbstractScanner, ScannerConfiguration, closeBraceInfoFor;
+    show
+        AbstractScanner,
+        LanguageVersionChanged,
+        ScannerConfiguration,
+        closeBraceInfoFor;
 
 import '../util/link.dart' show Link;
 
@@ -29,8 +33,9 @@
   bool hasErrors = false;
 
   ArrayBasedScanner(ScannerConfiguration config, bool includeComments,
-      {int numberOfBytesHint})
-      : super(config, includeComments, numberOfBytesHint: numberOfBytesHint);
+      LanguageVersionChanged languageVersionChanged, {int numberOfBytesHint})
+      : super(config, includeComments, languageVersionChanged,
+            numberOfBytesHint: numberOfBytesHint);
 
   /**
    * The stack of open groups, e.g [: { ... ( .. :]
diff --git a/pkg/front_end/lib/src/fasta/scanner/string_scanner.dart b/pkg/front_end/lib/src/fasta/scanner/string_scanner.dart
index 2b5c472..7fa5203 100644
--- a/pkg/front_end/lib/src/fasta/scanner/string_scanner.dart
+++ b/pkg/front_end/lib/src/fasta/scanner/string_scanner.dart
@@ -8,7 +8,8 @@
 
 import '../../scanner/token.dart' as analyzer show StringToken;
 
-import 'abstract_scanner.dart' show ScannerConfiguration;
+import 'abstract_scanner.dart'
+    show LanguageVersionChanged, ScannerConfiguration;
 
 import 'array_based_scanner.dart' show ArrayBasedScanner;
 
@@ -29,9 +30,11 @@
   int scanOffset = -1;
 
   StringScanner(String string,
-      {ScannerConfiguration configuration, bool includeComments: false})
+      {ScannerConfiguration configuration,
+      bool includeComments: false,
+      LanguageVersionChanged languageVersionChanged})
       : string = ensureZeroTermination(string),
-        super(configuration, includeComments);
+        super(configuration, includeComments, languageVersionChanged);
 
   static String ensureZeroTermination(String string) {
     return (string.isEmpty || string.codeUnitAt(string.length - 1) != 0)
diff --git a/pkg/front_end/lib/src/fasta/scanner/utf8_bytes_scanner.dart b/pkg/front_end/lib/src/fasta/scanner/utf8_bytes_scanner.dart
index 9aabe30..e847390 100644
--- a/pkg/front_end/lib/src/fasta/scanner/utf8_bytes_scanner.dart
+++ b/pkg/front_end/lib/src/fasta/scanner/utf8_bytes_scanner.dart
@@ -12,7 +12,8 @@
 
 import '../scanner.dart' show unicodeReplacementCharacter;
 
-import 'abstract_scanner.dart' show ScannerConfiguration;
+import 'abstract_scanner.dart'
+    show LanguageVersionChanged, ScannerConfiguration;
 
 import 'token.dart'
     show CommentToken, DartDocToken, LanguageVersionToken, StringToken;
@@ -85,8 +86,11 @@
    * is not the case, the entire array is copied before scanning.
    */
   Utf8BytesScanner(this.bytes,
-      {ScannerConfiguration configuration, bool includeComments: false})
-      : super(configuration, includeComments, numberOfBytesHint: bytes.length) {
+      {ScannerConfiguration configuration,
+      bool includeComments: false,
+      LanguageVersionChanged languageVersionChanged})
+      : super(configuration, includeComments, languageVersionChanged,
+            numberOfBytesHint: bytes.length) {
     assert(bytes.last == 0);
     // Skip a leading BOM.
     if (containsBomAt(0)) byteOffset += 3;
diff --git a/pkg/front_end/test/scanner_fasta_test.dart b/pkg/front_end/test/scanner_fasta_test.dart
index d4f785b..914ae8c 100644
--- a/pkg/front_end/test/scanner_fasta_test.dart
+++ b/pkg/front_end/test/scanner_fasta_test.dart
@@ -717,15 +717,26 @@
   ScannerResult scanSource(source, {includeComments: true}) {
     List<int> encoded = utf8.encode(source).toList(growable: true);
     encoded.add(0); // Ensure 0 terminted bytes for UTF8 scanner
-    return usedForFuzzTesting.scan(encoded, includeComments: includeComments);
+    return usedForFuzzTesting.scan(encoded,
+        includeComments: includeComments,
+        languageVersionChanged: languageVersionChanged);
   }
 }
 
 /// Scanner tests that exercise the Fasta scanner directly.
 @reflectiveTest
 class ScannerTest_Fasta_Direct extends ScannerTest_Fasta_Base {
+  LanguageVersionToken languageVersion;
+
+  void languageVersionChanged(
+      Scanner scanner, LanguageVersionToken languageVersion) {
+    this.languageVersion = languageVersion;
+  }
+
   ScannerResult scanSource(source, {includeComments: true}) =>
-      scanString(source, includeComments: includeComments);
+      scanString(source,
+          includeComments: includeComments,
+          languageVersionChanged: languageVersionChanged);
 
   @override
   Token scan(String source) {