diff --git a/agent/lib/src/commands/ci.dart b/agent/lib/src/commands/ci.dart
index e25c793e45..96d2b27c9d 100644
--- a/agent/lib/src/commands/ci.dart
+++ b/agent/lib/src/commands/ci.dart
@@ -110,7 +110,7 @@ class ContinuousIntegrationCommand extends Command {
   Future<Null> _screensOff() async {
     try {
       for (Device device in await devices.discoverDevices()) {
-        device.sendToSleep();
+        await device.sendToSleep();
       }
     } catch(error, stackTrace) {
       // Best effort only.