diff --git a/data/gui-en.xml b/data/gui-en.xml
index ad717f5be..9d2d6d55a 100644
--- a/data/gui-en.xml
+++ b/data/gui-en.xml
@@ -155,7 +155,7 @@
 	      </item>
 	      <item command="change_image_type" name="Indexed (Ordered &Dither)">
 		<param name="imgtype" value="indexed" />
-		<param name="dithering" value="on" />
+		<param name="dithering" value="ordered" />
 	      </item>
 	    </menu>
 	    <separator />
diff --git a/src/commands/cmd_change_image_type.cpp b/src/commands/cmd_change_image_type.cpp
index 29503a831..46cd10841 100644
--- a/src/commands/cmd_change_image_type.cpp
+++ b/src/commands/cmd_change_image_type.cpp
@@ -73,22 +73,25 @@ bool ChangeImageTypeCommand::enabled(Context* context)
 {
   const CurrentSpriteReader sprite(context);
 
-  if (sprite != NULL) {
-    if (sprite->imgtype == IMAGE_INDEXED && m_imgtype == IMAGE_INDEXED && m_dithering == DITHERING_NONE)
-      return false;
-  }
+  if (sprite != NULL &&
+      sprite->imgtype == IMAGE_INDEXED &&
+      m_imgtype == IMAGE_INDEXED &&
+      m_dithering == DITHERING_ORDERED)
+    return false;
 
-  return true;
+  return
+    sprite != NULL;
 }
 
 bool ChangeImageTypeCommand::checked(Context* context)
 {
   const CurrentSpriteReader sprite(context);
 
-  if (sprite != NULL) {
-    if (sprite->imgtype == IMAGE_INDEXED && m_imgtype == IMAGE_INDEXED && m_dithering == DITHERING_NONE)
-      return false;
-  }
+  if (sprite != NULL &&
+      sprite->imgtype == IMAGE_INDEXED &&
+      m_imgtype == IMAGE_INDEXED &&
+      m_dithering == DITHERING_ORDERED)
+    return false;
 
   return
     sprite != NULL &&