diff --git a/data/widgets/layer_properties.xml b/data/widgets/layer_properties.xml
index 6a7033edb..4ab12279d 100644
--- a/data/widgets/layer_properties.xml
+++ b/data/widgets/layer_properties.xml
@@ -14,7 +14,7 @@
       <button id="tileset" icon="tiles" tooltip="@.tileset_tooltip" />
 
       <label text="@.opacity" />
-      <slider id="opacity" min="0" max="255" width="128" cell_align="horizontal" cell_hspan="2" />
+      <opacityslider id="opacity" width="128" cell_align="horizontal" cell_hspan="2" />
     </grid>
   </vbox>
 </window>
diff --git a/data/widgets/timeline_conf.xml b/data/widgets/timeline_conf.xml
index 6fa4c737e..8f2261430 100644
--- a/data/widgets/timeline_conf.xml
+++ b/data/widgets/timeline_conf.xml
@@ -43,10 +43,10 @@
     </hbox>
 
     <label text="@.opacity" />
-    <slider min="0" max="255" id="opacity" cell_align="horizontal" width="128" />
+    <opacityslider id="opacity" cell_align="horizontal" width="128" />
 
     <label text="@.opacity_step" />
-    <slider min="0" max="255" id="opacity_step" cell_align="horizontal" width="128" />
+    <opacityslider id="opacity_step" cell_align="horizontal" width="128" />
 
     <check id="loop_tag" text="@.loop_tags" cell_hspan="2" />
     <check id="current_layer" text="@.current_layer" cell_hspan="2" />