diff --git a/layout/reftests/invalidation/scroll-inactive-layers.html b/layout/reftests/invalidation/scroll-inactive-layers.html
index 84a5808aa0be..7b658b6fc568 100644
--- a/layout/reftests/invalidation/scroll-inactive-layers.html
+++ b/layout/reftests/invalidation/scroll-inactive-layers.html
@@ -1,5 +1,9 @@
 <!DOCTYPE html>
-<html class="reftest-wait">
+<html class="reftest-wait"
+      reftest-displayport-x="0"
+      reftest-displayport-y="0"
+      reftest-displayport-w="800"
+      reftest-displayport-h="1000">
 <title>Scrolling over inactive layers shouldn't repaint their contents</title>
 
 <style>
