diff --git a/lib/src/importer/js_to_dart/async.dart b/lib/src/importer/js_to_dart/async.dart
index e34a7419e..c6d26cbe2 100644
--- a/lib/src/importer/js_to_dart/async.dart
+++ b/lib/src/importer/js_to_dart/async.dart
@@ -13,6 +13,7 @@ import '../../js/url.dart';
 import '../../js/utils.dart';
 import '../../util/nullable.dart';
 import '../async.dart';
+import '../canonicalize_context.dart';
 import '../result.dart';
 import 'utils.dart';
 
@@ -20,7 +21,7 @@ import 'utils.dart';
 /// a Dart [AsyncImporter].
 final class JSToDartAsyncImporter extends AsyncImporter {
   /// The wrapped canonicalize function.
-  final Object? Function(String, JSCanonicalizeContext) _canonicalize;
+  final Object? Function(String, CanonicalizeContext) _canonicalize;
 
   /// The wrapped load function.
   final Object? Function(JSUrl) _load;
@@ -38,8 +39,8 @@ final class JSToDartAsyncImporter extends AsyncImporter {
   }
 
   FutureOr<Uri?> canonicalize(Uri url) async {
-    var result = wrapJSExceptions(() => _canonicalize(
-        url.toString(), dartToJSCanonicalizeContext(canonicalizeContext)));
+    var result = wrapJSExceptions(
+        () => _canonicalize(url.toString(), canonicalizeContext));
     if (isPromise(result)) result = await promiseToFuture(result as Promise);
     if (result == null) return null;
 
diff --git a/lib/src/importer/js_to_dart/async_file.dart b/lib/src/importer/js_to_dart/async_file.dart
index af7a3fa57..95b2af908 100644
--- a/lib/src/importer/js_to_dart/async_file.dart
+++ b/lib/src/importer/js_to_dart/async_file.dart
@@ -8,10 +8,10 @@ import 'package:cli_pkg/js.dart';
 import 'package:node_interop/js.dart';
 import 'package:node_interop/util.dart';
 
-import '../../js/importer.dart';
 import '../../js/url.dart';
 import '../../js/utils.dart';
 import '../async.dart';
+import '../canonicalize_context.dart';
 import '../filesystem.dart';
 import '../result.dart';
 import '../utils.dart';
@@ -20,15 +20,15 @@ import '../utils.dart';
 /// it as a Dart [AsyncImporter].
 final class JSToDartAsyncFileImporter extends AsyncImporter {
   /// The wrapped `findFileUrl` function.
-  final Object? Function(String, JSCanonicalizeContext) _findFileUrl;
+  final Object? Function(String, CanonicalizeContext) _findFileUrl;
 
   JSToDartAsyncFileImporter(this._findFileUrl);
 
   FutureOr<Uri?> canonicalize(Uri url) async {
     if (url.scheme == 'file') return FilesystemImporter.cwd.canonicalize(url);
 
-    var result = wrapJSExceptions(() => _findFileUrl(
-        url.toString(), dartToJSCanonicalizeContext(canonicalizeContext)));
+    var result = wrapJSExceptions(
+        () => _findFileUrl(url.toString(), canonicalizeContext));
     if (isPromise(result)) result = await promiseToFuture(result as Promise);
     if (result == null) return null;
     if (!isJSUrl(result)) {
diff --git a/lib/src/importer/js_to_dart/file.dart b/lib/src/importer/js_to_dart/file.dart
index 8b271fb01..555c9df16 100644
--- a/lib/src/importer/js_to_dart/file.dart
+++ b/lib/src/importer/js_to_dart/file.dart
@@ -6,24 +6,24 @@ import 'package:cli_pkg/js.dart';
 import 'package:node_interop/js.dart';
 
 import '../../importer.dart';
-import '../../js/importer.dart';
 import '../../js/url.dart';
 import '../../js/utils.dart';
+import '../canonicalize_context.dart';
 import '../utils.dart';
 
 /// A wrapper for a potentially-asynchronous JS API file importer that exposes
 /// it as a Dart [AsyncImporter].
 final class JSToDartFileImporter extends Importer {
   /// The wrapped `findFileUrl` function.
-  final Object? Function(String, JSCanonicalizeContext) _findFileUrl;
+  final Object? Function(String, CanonicalizeContext) _findFileUrl;
 
   JSToDartFileImporter(this._findFileUrl);
 
   Uri? canonicalize(Uri url) {
     if (url.scheme == 'file') return FilesystemImporter.cwd.canonicalize(url);
 
-    var result = wrapJSExceptions(() => _findFileUrl(
-        url.toString(), dartToJSCanonicalizeContext(canonicalizeContext)));
+    var result = wrapJSExceptions(
+        () => _findFileUrl(url.toString(), canonicalizeContext));
     if (result == null) return null;
 
     if (isPromise(result)) {
diff --git a/lib/src/importer/js_to_dart/sync.dart b/lib/src/importer/js_to_dart/sync.dart
index ad302af1a..06b91310a 100644
--- a/lib/src/importer/js_to_dart/sync.dart
+++ b/lib/src/importer/js_to_dart/sync.dart
@@ -10,13 +10,14 @@ import '../../js/importer.dart';
 import '../../js/url.dart';
 import '../../js/utils.dart';
 import '../../util/nullable.dart';
+import '../canonicalize_context.dart';
 import 'utils.dart';
 
 /// A wrapper for a synchronous JS API importer that exposes it as a Dart
 /// [Importer].
 final class JSToDartImporter extends Importer {
   /// The wrapped canonicalize function.
-  final Object? Function(String, JSCanonicalizeContext) _canonicalize;
+  final Object? Function(String, CanonicalizeContext) _canonicalize;
 
   /// The wrapped load function.
   final Object? Function(JSUrl) _load;
@@ -34,8 +35,8 @@ final class JSToDartImporter extends Importer {
   }
 
   Uri? canonicalize(Uri url) {
-    var result = wrapJSExceptions(() => _canonicalize(
-        url.toString(), dartToJSCanonicalizeContext(canonicalizeContext)));
+    var result = wrapJSExceptions(
+        () => _canonicalize(url.toString(), canonicalizeContext));
     if (result == null) return null;
     if (isJSUrl(result)) return jsToDartUrl(result as JSUrl);
 
diff --git a/lib/src/js.dart b/lib/src/js.dart
index 79bf90180..dc0384bc4 100644
--- a/lib/src/js.dart
+++ b/lib/src/js.dart
@@ -7,6 +7,7 @@ import 'package:js/js_util.dart';
 import 'js/exception.dart';
 import 'js/deprecations.dart';
 import 'js/exports.dart';
+import 'js/importer/canonicalize_context.dart';
 import 'js/compile.dart';
 import 'js/compiler.dart';
 import 'js/legacy.dart';
@@ -64,6 +65,7 @@ void main() {
       "dart2js\t${const String.fromEnvironment('dart-version')}\t"
       "(Dart Compiler)\t[Dart]";
 
+  updateCanonicalizeContextPrototype();
   updateSourceSpanPrototype();
 
   // Legacy API
diff --git a/lib/src/js/importer.dart b/lib/src/js/importer.dart
index 42d5aff90..09ffcd665 100644
--- a/lib/src/js/importer.dart
+++ b/lib/src/js/importer.dart
@@ -4,24 +4,18 @@
 
 import 'package:js/js.dart';
 
+import '../importer/canonicalize_context.dart';
 import 'url.dart';
 
 @JS()
 @anonymous
 class JSImporter {
-  external Object? Function(String, JSCanonicalizeContext)? get canonicalize;
+  external Object? Function(String, CanonicalizeContext)? get canonicalize;
   external Object? Function(JSUrl)? get load;
-  external Object? Function(String, JSCanonicalizeContext)? get findFileUrl;
+  external Object? Function(String, CanonicalizeContext)? get findFileUrl;
   external Object? get nonCanonicalScheme;
 }
 
-@JS()
-@anonymous
-class JSCanonicalizeContext {
-  external bool get fromImport;
-  external JSUrl? get containingUrl;
-}
-
 @JS()
 @anonymous
 class JSImporterResult {
diff --git a/lib/src/js/importer/canonicalize_context.dart b/lib/src/js/importer/canonicalize_context.dart
index 9b7d115e1..412f21ce8 100644
--- a/lib/src/js/importer/canonicalize_context.dart
+++ b/lib/src/js/importer/canonicalize_context.dart
@@ -2,20 +2,15 @@
 // MIT-style license that can be found in the LICENSE file or at
 // https://opensource.org/licenses/MIT.
 
-import 'package:js/js.dart';
-
 import '../../importer/canonicalize_context.dart';
-import '../url.dart';
 import '../../util/nullable.dart';
+import '../reflection.dart';
 import '../utils.dart';
 
-@JSExport()
-class JSExportCanonicalizeContext {
-  final CanonicalizeContext _canonicalizeContext;
-
-  bool get fromImport => _canonicalizeContext.fromImport;
-  JSUrl? get containingUrl =>
-      _canonicalizeContext.containingUrl.andThen(dartToJSUrl);
-
-  JSExportCanonicalizeContext(this._canonicalizeContext);
-}
+/// Adds JS members to Dart's `CanonicalizeContext` class.
+void updateCanonicalizeContextPrototype() =>
+    getJSClass(CanonicalizeContext(null, false)).defineGetters({
+      'fromImport': (CanonicalizeContext self) => self.fromImport,
+      'containingUrl': (CanonicalizeContext self) =>
+          self.containingUrl.andThen(dartToJSUrl),
+    });
diff --git a/lib/src/js/utils.dart b/lib/src/js/utils.dart
index 62e6edd24..a6b269782 100644
--- a/lib/src/js/utils.dart
+++ b/lib/src/js/utils.dart
@@ -9,14 +9,11 @@ import 'package:node_interop/node.dart' hide module;
 import 'package:js/js.dart';
 import 'package:js/js_util.dart';
 
-import '../importer/canonicalize_context.dart';
 import '../syntax.dart';
 import '../utils.dart';
 import '../value.dart';
 import 'array.dart';
 import 'function.dart';
-import 'importer.dart';
-import 'importer/canonicalize_context.dart';
 import 'module.dart';
 import 'reflection.dart';
 import 'url.dart';
@@ -200,12 +197,6 @@ Uri jsToDartUrl(JSUrl url) => Uri.parse(url.toString());
 /// Converts a Dart [Uri] object to a standard JS `URL` object.
 JSUrl dartToJSUrl(Uri url) => JSUrl(url.toString());
 
-JSCanonicalizeContext dartToJSCanonicalizeContext(
-    CanonicalizeContext canonicalizeContext) {
-  return createDartExport(JSExportCanonicalizeContext(canonicalizeContext))
-      as JSCanonicalizeContext;
-}
-
 /// Creates a JavaScript array containing [iterable].
 ///
 /// While Dart arrays are notionally compatible with JS arrays, they still have
diff --git a/lib/src/js/value/mixin.dart b/lib/src/js/value/mixin.dart
index a41b394d2..cc55f3eb4 100644
--- a/lib/src/js/value/mixin.dart
+++ b/lib/src/js/value/mixin.dart
@@ -13,7 +13,8 @@ import '../utils.dart';
 final JSClass mixinClass = () {
   var jsClass = createJSClass('sass.SassMixin', (Object self) {
     jsThrow(JsError(
-        'It is not possible to construct a SassMixin through the JavaScript API'));
+        'It is not possible to construct a SassMixin through the JavaScript '
+        'API'));
   });
 
   getJSClass(SassMixin(Callable('f', '', (_) => sassNull)))