diff --git a/tests/reftests/label-sizing.ref.ui b/tests/reftests/label-sizing.ref.ui
index 7d42ad2461..2de71a4a5a 100644
--- a/tests/reftests/label-sizing.ref.ui
+++ b/tests/reftests/label-sizing.ref.ui
@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <interface>
   <!-- interface-requires gtk+ 3.0 -->
-  <object class="GtkWindow" id="window1">
+  <object class="GtkOffscreenWindow" id="window1">
     <property name="can_focus">False</property>
     <property name="type">popup</property>
     <child>
diff --git a/tests/reftests/label-sizing.ui b/tests/reftests/label-sizing.ui
index 3682291104..9031bfe6f6 100644
--- a/tests/reftests/label-sizing.ui
+++ b/tests/reftests/label-sizing.ui
@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <interface>
   <!-- interface-requires gtk+ 3.0 -->
-  <object class="GtkWindow" id="window1">
+  <object class="GtkOffscreenWindow" id="window1">
     <property name="can_focus">False</property>
     <property name="type">popup</property>
     <child>