diff --git a/lib/Properties.hs b/lib/Properties.hs
index 1d8731170ab4189922099320217f4534d3f13b99..a4465d46df71c02215d20fa8b572497d42349150 100644
--- a/lib/Properties.hs
+++ b/lib/Properties.hs
@@ -117,8 +117,8 @@ checkTileset = do
   when (isJust (tilesetSource tileset))
     $ complain "Tilesets must be embedded and cannot be loaded from external files."
   -- TODO: check copyright!
-  unlessHasProperty "copyright"
-    $ forbid "property \"copyright\" is required for tilesets."
+  unlessHasProperty "tiledCopyright"
+    $ forbid "property \"tiledCopyright\" for tilesets must be set."
 
   -- check individual tileset properties
   mapM_ checkTilesetProperty (fromMaybe [] $ tilesetProperties tileset)