diff --git a/packages/ferry_generator/lib/graphql_builder.dart b/packages/ferry_generator/lib/graphql_builder.dart
index 5aeb676b..8997ca55 100644
--- a/packages/ferry_generator/lib/graphql_builder.dart
+++ b/packages/ferry_generator/lib/graphql_builder.dart
@@ -4,17 +4,17 @@ import 'package:build/build.dart';
 import 'package:code_builder/code_builder.dart';
 import 'package:gql_code_builder/ast.dart';
 import 'package:gql_code_builder/data.dart';
-import 'package:gql_code_builder/var.dart';
 import 'package:gql_code_builder/schema.dart';
+import 'package:gql_code_builder/var.dart';
 import 'package:path/path.dart' as p;
 
-import 'src/utils/locations.dart';
+import 'src/allocators/gql_allocator.dart';
+import 'src/codegen/req.dart';
+import 'src/utils/add_introspection.dart';
 import 'src/utils/config.dart';
+import 'src/utils/locations.dart';
 import 'src/utils/reader.dart';
 import 'src/utils/writer.dart';
-import 'src/utils/add_introspection.dart';
-import 'src/codegen/req.dart';
-import 'src/allocators/gql_allocator.dart';
 
 Builder graphqlBuilder(
   BuilderOptions options,
@@ -55,6 +55,21 @@ class GraphqlBuilder implements Builder {
           'When extensions require add_typenames to be true. Consider setting add_typenames to true in your build.yaml or disabling when_extensions in your build.yaml.');
     }
 
+    final schemaOutputAsset =
+        outputAssetId(config.schemaId, schemaExtension, config.outputDir);
+
+    final schemaUrl = schemaOutputAsset.uri.toString();
+    final schemaAllocator = GqlAllocator(
+      buildStep.inputId.uri.toString(),
+      config.sourceExtension,
+      outputAssetId(buildStep.inputId, schemaExtension, config.outputDir)
+          .uri
+          .toString(),
+      schemaUrl,
+      config.outputDir,
+    );
+
+    final varAllocator = schemaAllocator;
     final libs = <String, Library>{
       astExtension: buildAstLibrary(doc),
       dataExtension: buildDataLibrary(
@@ -65,11 +80,12 @@ class GraphqlBuilder implements Builder {
         config.whenExtensionConfig,
       ),
       varExtension: buildVarLibrary(
-        doc,
-        addTypenames(schema),
-        p.basename(generatedFilePath(buildStep.inputId, varExtension)),
-        config.typeOverrides,
-      ),
+          doc,
+          addTypenames(schema),
+          p.basename(generatedFilePath(buildStep.inputId, varExtension)),
+          config.typeOverrides,
+          config.serializeNulls,
+          varAllocator),
       reqExtension: buildReqLibrary(
         doc,
         p.basename(generatedFilePath(buildStep.inputId, reqExtension)),
@@ -80,6 +96,7 @@ class GraphqlBuilder implements Builder {
         config.typeOverrides,
         config.enumFallbackConfig,
         generatePossibleTypesMap: config.shouldGeneratePossibleTypes,
+        allocator: schemaAllocator,
       ),
     };
 
@@ -89,13 +106,17 @@ class GraphqlBuilder implements Builder {
       final schemaOutputAsset =
           outputAssetId(config.schemaId, schemaExtension, config.outputDir);
 
-      final allocator = GqlAllocator(
-        buildStep.inputId.uri.toString(),
-        config.sourceExtension,
-        generatedAsset.uri.toString(),
-        schemaOutputAsset.uri.toString(),
-        config.outputDir,
-      );
+      final allocator = entry.key == schemaExtension
+          ? schemaAllocator
+          : entry.key == varExtension
+              ? varAllocator
+              : GqlAllocator(
+                  buildStep.inputId.uri.toString(),
+                  config.sourceExtension,
+                  generatedAsset.uri.toString(),
+                  schemaOutputAsset.uri.toString(),
+                  config.outputDir,
+                );
 
       await writeDocument(generatedAsset, entry.value, allocator, buildStep);
     }
diff --git a/packages/ferry_generator/lib/src/utils/config.dart b/packages/ferry_generator/lib/src/utils/config.dart
index 7c1f9477..78c3b2b8 100644
--- a/packages/ferry_generator/lib/src/utils/config.dart
+++ b/packages/ferry_generator/lib/src/utils/config.dart
@@ -14,6 +14,7 @@ class BuilderConfig {
   final AssetId schemaId;
   final bool shouldAddTypenames;
   final bool shouldGeneratePossibleTypes;
+  final bool serializeNulls;
   final Map<String, Reference> typeOverrides;
   final Set<Reference> customSerializers;
   final EnumFallbackConfig enumFallbackConfig;
@@ -27,6 +28,7 @@ class BuilderConfig {
         typeOverrides = _getTypeOverrides(config['type_overrides']),
         shouldGeneratePossibleTypes =
             config['generate_possible_types_map'] ?? true,
+        serializeNulls = config['serialize_nulls'] ?? false,
         customSerializers = _getCustomSerializers(config['custom_serializers']),
         enumFallbackConfig = _getEnumFallbackConfig(config),
         outputDir = config['output_dir'] ?? '__generated__',
diff --git a/packages/ferry_generator/pubspec.yaml b/packages/ferry_generator/pubspec.yaml
index 9f0accbd..0b78caba 100644
--- a/packages/ferry_generator/pubspec.yaml
+++ b/packages/ferry_generator/pubspec.yaml
@@ -19,8 +19,17 @@ dependencies:
   built_value_generator: ^8.1.1
   built_value: ^8.1.2
   analyzer: ">=4.2.0 <6.0.0"
+
 dev_dependencies:
   test: ^1.16.8
   build_runner: ^2.0.2
   build_test: ^2.0.0
   pedantic: ^1.11.0
+
+
+dependency_overrides:
+  gql_code_builder:
+    git:
+      url: https://github.com/twklessor/gql.git
+      ref: feature/serialize-nulls
+      path: codegen/gql_code_builder