diff --git a/thermion_dart/lib/thermion_dart/thermion_viewer_stub.dart b/thermion_dart/lib/thermion_dart/thermion_viewer_stub.dart
index a04127d1..fc6e0b02 100644
--- a/thermion_dart/lib/thermion_dart/thermion_viewer_stub.dart
+++ b/thermion_dart/lib/thermion_dart/thermion_viewer_stub.dart
@@ -537,7 +537,7 @@ class ThermionViewerStub extends ThermionViewer {
   }
 
   @override
-  Future setCameraFov(double degrees, double width, double height) {
+  Future setCameraFov(double degrees, {bool horizontal=true}) {
     // TODO: implement setCameraFov
     throw UnimplementedError();
   }