diff --git a/packages/flutter_tools/lib/src/test/flutter_platform.dart b/packages/flutter_tools/lib/src/test/flutter_platform.dart
index 1bec9a00be0..e01414e47ab 100644
--- a/packages/flutter_tools/lib/src/test/flutter_platform.dart
+++ b/packages/flutter_tools/lib/src/test/flutter_platform.dart
@@ -84,7 +84,7 @@ void installHook({
   InternetAddressType serverType = InternetAddressType.IPv4,
   Uri projectRootDirectory,
 }) {
-  assert(!enableObservatory || (!startPaused && observatoryPort == null));
+  assert(enableObservatory || (!startPaused && observatoryPort == null));
   hack.registerPlatformPlugin(
     <Runtime>[Runtime.vm],
     () => _FlutterPlatform(