diff --git a/frappe/model/mapper.py b/frappe/model/mapper.py
index 6d0cba2044..5b727d8593 100644
--- a/frappe/model/mapper.py
+++ b/frappe/model/mapper.py
@@ -103,6 +103,8 @@ def get_mapped_doc(
 		if not source_doc.has_permission("read"):
 			source_doc.raise_no_permission_to("read")
 
+	ret_doc.run_method("before_mapping", source_doc, table_maps)
+
 	map_doc(source_doc, target_doc, table_maps[source_doc.doctype])
 
 	row_exists_for_parentfield = {}