diff --git a/lib/Properties.hs b/lib/Properties.hs
index c106b9f968448b0df66813129523d3bb7d91c7ac..bb18499cce63ec2c7775b380ef5c865bdecf6a6e 100644
--- a/lib/Properties.hs
+++ b/lib/Properties.hs
@@ -58,6 +58,7 @@ checkMap = do
   -- not specific to any one of them
   refuseDoubledNames (tiledmapLayers tiledmap)
   refuseDoubledNames (tiledmapTilesets tiledmap)
+  refuseDoubledNames (getProperties tiledmap)
 
   -- some layers should exist
   unlessElementNamed (tiledmapLayers tiledmap) "start"
@@ -161,7 +162,7 @@ checkLayer :: LintWriter Layer
 checkLayer = do
   layer <- askContext
 
-  refuseDoubledNames (getProperties  layer)
+  refuseDoubledNames (getProperties layer)
 
   when (isJust (layerImage layer))
     $ complain "imagelayer are not supported."