diff --git a/dwds/test/fixtures/context.dart b/dwds/test/fixtures/context.dart
index 07144df7e..f563ddc29 100644
--- a/dwds/test/fixtures/context.dart
+++ b/dwds/test/fixtures/context.dart
@@ -229,6 +229,7 @@ class TestContext {
       String basePath = '';
 
       _port = await findUnusedPort();
+      final soundNullSafety = nullSafety == NullSafety.sound;
       switch (compilationMode) {
         case CompilationMode.buildDaemon:
           {
@@ -237,6 +238,8 @@ class TestContext {
                 '--define',
                 'build_web_compilers|ddc=generate-full-dill=true',
               ],
+              '--define',
+              'build_web_compilers:entrypoint=sound_null_safety=$soundNullSafety',
               '--verbose',
             ];
             _daemonClient =
diff --git a/dwds/test/utils/version_compatibility.dart b/dwds/test/utils/version_compatibility.dart
index 1ff63ae81..6206a07da 100644
--- a/dwds/test/utils/version_compatibility.dart
+++ b/dwds/test/utils/version_compatibility.dart
@@ -2,21 +2,11 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-import 'dart:io';
-
-import 'package:pub_semver/pub_semver.dart';
-
 import '../fixtures/context.dart';
 
 bool supportedMode(
     {required CompilationMode compilationMode,
     required NullSafety nullSafetyMode}) {
-  final isDart3 = Version.parse(Platform.version.split(' ')[0]).major == 3;
-  // TODO(https://github.com/dart-lang/webdev/issues/1818): Support compiling to
-  // to weak null-safety for both FrontendServer and BuildDaemon.
-  if (isDart3 && nullSafetyMode == NullSafety.weak) {
-    return false;
-  }
   // TODO(https://github.com/dart-lang/webdev/issues/1591): Support compiling to
   // sound null-safety for the FrontendServer.
   if (compilationMode == CompilationMode.frontendServer &&
diff --git a/frontend_server_common/lib/src/frontend_server_client.dart b/frontend_server_common/lib/src/frontend_server_client.dart
index 321c6ac14..fd69a7abc 100644
--- a/frontend_server_common/lib/src/frontend_server_client.dart
+++ b/frontend_server_common/lib/src/frontend_server_client.dart
@@ -259,6 +259,7 @@ class ResidentCompiler {
     required this.fileSystemRoots,
     required this.fileSystemScheme,
     required this.platformDill,
+    required this.soundNullSafety,
     this.verbose = false,
     CompilerMessageConsumer compilerMessageConsumer = defaultConsumer,
   }) : _stdoutHandler = StdoutHandler(consumer: compilerMessageConsumer);
@@ -269,6 +270,7 @@ class ResidentCompiler {
   final List<Uri> fileSystemRoots;
   final String fileSystemScheme;
   final String platformDill;
+  final bool soundNullSafety;
   final bool verbose;
 
   /// The path to the root of the Dart SDK used to compile.
@@ -386,6 +388,8 @@ class ResidentCompiler {
       ],
       if (useDebuggerModuleNames) '--debugger-module-names',
       '--experimental-emit-debug-metadata',
+      if (soundNullSafety) '--sound-null-safety',
+      if (!soundNullSafety) '--no-sound-null-safety',
       if (verbose) '--verbose'
     ];
 
diff --git a/frontend_server_common/lib/src/resident_runner.dart b/frontend_server_common/lib/src/resident_runner.dart
index 16c793b8a..a369f1b9f 100644
--- a/frontend_server_common/lib/src/resident_runner.dart
+++ b/frontend_server_common/lib/src/resident_runner.dart
@@ -46,6 +46,7 @@ class ResidentWebRunner {
       fileSystemRoots: fileSystemRoots,
       fileSystemScheme: fileSystemScheme,
       verbose: verbose,
+      soundNullSafety: soundNullSafety,
     );
     expressionCompiler = TestExpressionCompiler(generator);
   }