diff --git a/reclass/datatypes/parameters.py b/reclass/datatypes/parameters.py
index 718f41f..7467594 100644
--- a/reclass/datatypes/parameters.py
+++ b/reclass/datatypes/parameters.py
@@ -57,7 +57,7 @@
                 self.merge(mapping)
                 self._keep_overrides = False
             else:
-                self._base = mapping
+                self._base = copy.deepcopy(mapping)
 
     #delimiter = property(lambda self: self._delimiter)