diff --git a/src/Filters/Rules/Person/_HasCommonAncestorWith.py b/src/Filters/Rules/Person/_HasCommonAncestorWith.py
index d6bfc3f3c..e81954ba2 100644
--- a/src/Filters/Rules/Person/_HasCommonAncestorWith.py
+++ b/src/Filters/Rules/Person/_HasCommonAncestorWith.py
@@ -72,15 +72,19 @@ class HasCommonAncestorWith(Rule):
             return
 
         for fam_handle in person.get_parent_family_handle_list():
+            parentless_fam = True
             fam = db.get_family_from_handle(fam_handle)
             if fam:
                 for par_handle in (fam.get_father_handle(), fam.get_mother_handle()):
                     if par_handle:
+                        parentless_fam = False
                         par = db.get_person_from_handle(par_handle)
                         if par and par.handle not in self.ancestor_cache:
                             self.add_ancs(db, par)
                         if par:
                             self.ancestor_cache[person.handle] |= self.ancestor_cache[par.handle]
+                if parentless_fam:
+                    self.ancestor_cache[person.handle].add(fam_handle)
 
     def reset(self):
         self.ancestor_cache = {}