diff --git a/packages/flutter_tools/test/src/fakes.dart b/packages/flutter_tools/test/src/fakes.dart
index 33dfdb554ab..e7f38c93d98 100644
--- a/packages/flutter_tools/test/src/fakes.dart
+++ b/packages/flutter_tools/test/src/fakes.dart
@@ -193,6 +193,13 @@ class MemoryStdout extends MemoryIOSink implements io.Stdout {
   }
   bool _hasTerminal = true;
 
+  @override
+  // ignore: override_on_non_overriding_member
+  String get lineTerminator => '\n';
+  set lineTerminator(String value) {
+    throw UnimplementedError('Setting the line terminator is not supported');
+  }
+
   @override
   io.IOSink get nonBlocking => this;