diff --git a/lib/Properties.hs b/lib/Properties.hs
index aafe61c03878d3677a5dc98336a09b67c9069105..04cc26f0aa6c3bd81248efb97cc8d3c1fd1d15b9 100644
--- a/lib/Properties.hs
+++ b/lib/Properties.hs
@@ -209,6 +209,8 @@ checkTileset = do
               "collides" -> isBool p
               -- named tiles are needed for scripting and do not hurt otherwise
               "name" -> isString p
+              "tilesetCopyright" -> warn "the \"tilesetCopyright\" property should be set on the entire tileset, \
+                                         \not an individual tile."
               _ -> warnUnknown' ("unknown tile property "
                       <> prettyprint name <> " in tile with global id "
                       <> showText (tileId tile)) p knownTilesetProperties