diff --git a/lib/forwarder.dart b/lib/forwarder.dart
index 05dd72f..a136237 100644
--- a/lib/forwarder.dart
+++ b/lib/forwarder.dart
@@ -18,7 +18,7 @@
 class WipForwarder {
   static final _log = new Logger('ChromeForwarder');
 
-  final Stream _in;
+  final Stream<String> _in;
   final StreamSink _out;
   final WipConnection _debugger;
   final WipDom domModel;