diff --git a/pytiled_parser/xml_parser.py b/pytiled_parser/xml_parser.py
index 63b0796..e89b849 100644
--- a/pytiled_parser/xml_parser.py
+++ b/pytiled_parser/xml_parser.py
@@ -483,6 +483,7 @@ def _parse_tiles(
         except KeyError:
             pass
 
+        terrain = None
         try:
             tile_terrain_attrib = tile_element.attrib["terrain"]
         except KeyError: