diff --git a/tools/testing/dart/compiler_configuration.dart b/tools/testing/dart/compiler_configuration.dart
index 1ca96e7e322..5cce89d5e5d 100644
--- a/tools/testing/dart/compiler_configuration.dart
+++ b/tools/testing/dart/compiler_configuration.dart
@@ -1163,7 +1163,7 @@ class FastaCompilerConfiguration extends CompilerConfiguration {
       List<String> dart2jsOptions,
       List<String> ddcOptions,
       List<String> args) {
-    List<String> arguments = <String>[];
+    List<String> arguments = new List<String>.from(sharedOptions);
     for (String argument in args) {
       if (argument == "--ignore-unrecognized-flags") continue;
       arguments.add(argument);
diff --git a/tools/testing/dart/test_suite.dart b/tools/testing/dart/test_suite.dart
index 3cd18ab2447..0428eff632c 100644
--- a/tools/testing/dart/test_suite.dart
+++ b/tools/testing/dart/test_suite.dart
@@ -1184,6 +1184,10 @@ class StandardTestSuite extends TestSuite {
     assert(!isMultitest || dartOptions == null);
     args.add(filePath.toNativePath());
     if (dartOptions != null) {
+      // TODO(ahe): Because we add [dartOptions] here,
+      // [CompilerConfiguration.computeCompilerArguments] has to discard them
+      // later. Perhaps it would be simpler to pass [dartOptions] to
+      // [CompilerConfiguration.computeRuntimeArguments].
       args.addAll(dartOptions);
     }