diff --git a/packages/dynamite/dynamite_runtime/lib/src/client/client.dart b/packages/dynamite/dynamite_runtime/lib/src/client/client.dart
index 5207627fc4c..862ffcd0ad6 100644
--- a/packages/dynamite/dynamite_runtime/lib/src/client/client.dart
+++ b/packages/dynamite/dynamite_runtime/lib/src/client/client.dart
@@ -62,7 +62,22 @@ class DynamiteClient with http.BaseClient {
     if (cookieJar != null) {
       final cookies = await cookieJar!.loadForRequest(request.url);
       if (cookies.isNotEmpty) {
-        request.headers['cookie'] = cookies.join('; ');
+        final buffer = StringBuffer();
+
+        for (final entry in cookies.indexed) {
+          final cookie = entry.$2;
+
+          buffer
+            ..write(cookie.name)
+            ..write('=')
+            ..write(cookie.value);
+
+          if (entry.$1 < cookies.length - 1) {
+            buffer.write('; ');
+          }
+        }
+
+        request.headers['cookie'] = buffer.toString();
       }
     }
 
diff --git a/packages/dynamite/dynamite_runtime/test/client_test.dart b/packages/dynamite/dynamite_runtime/test/client_test.dart
index f563cc7ced5..b16c9e72668 100644
--- a/packages/dynamite/dynamite_runtime/test/client_test.dart
+++ b/packages/dynamite/dynamite_runtime/test/client_test.dart
@@ -15,7 +15,7 @@ void main() {
 
     test('Cookies', () async {
       final mockedClient = MockClient((request) async {
-        expect(request.headers['cookie'], equals(Cookie('a', 'b').toString()));
+        expect(request.headers['cookie'], equals('a=b; a2=b2; a3=b3'));
 
         return Response(
           '',
@@ -32,15 +32,19 @@ void main() {
         cookieJar: cookieJar,
       );
 
-      await cookieJar.saveFromResponse(uri, [Cookie('a', 'b')]);
+      await cookieJar.saveFromResponse(uri, [
+        Cookie('a', 'b'),
+        Cookie('a2', 'b2'),
+        Cookie('a3', 'b3'),
+      ]);
       await client.get(uri);
 
       final cookies = await cookieJar.loadForRequest(uri);
-      expect(cookies, hasLength(2));
+      expect(cookies, hasLength(4));
       expect(cookies[0].name, 'a');
       expect(cookies[0].value, 'b');
-      expect(cookies[1].name, 'c');
-      expect(cookies[1].value, 'd');
+      expect(cookies.last.name, 'c');
+      expect(cookies.last.value, 'd');
     });
 
     test('No cookies', () async {