diff --git a/gramps/plugins/tool/finddupes.py b/gramps/plugins/tool/finddupes.py
index 497692289..9008d970a 100644
--- a/gramps/plugins/tool/finddupes.py
+++ b/gramps/plugins/tool/finddupes.py
@@ -193,6 +193,7 @@ class DuplicatePeopleTool(tool.Tool, ManagedWindow):
         index = 0
         males = {}
         females = {}
+        self.map = {}
 
         length = self.db.get_number_of_people()