diff --git a/src/ifcopenshell-python/ifcopenshell/api/void/add_filling.py b/src/ifcopenshell-python/ifcopenshell/api/void/add_filling.py
index 33784b4cfa..64fee4a19e 100644
--- a/src/ifcopenshell-python/ifcopenshell/api/void/add_filling.py
+++ b/src/ifcopenshell-python/ifcopenshell/api/void/add_filling.py
@@ -9,6 +9,13 @@ class Usecase:
             self.settings[key] = value
 
     def execute(self):
+        fills_voids = self.settings["element"].FillsVoids
+
+        if fills_voids:
+            if fills_voids[0].RelatingOpeningElement == self.settings["opening"]:
+                return
+            self.file.remove(fills_voids[0])
+
         self.file.create_entity(
             "IfcRelFillsElement",
             **{
diff --git a/src/ifcopenshell-python/test/api/void/test_add_filling.py b/src/ifcopenshell-python/test/api/void/test_add_filling.py
new file mode 100644
index 0000000000..b3d5bbf0cb
--- /dev/null
+++ b/src/ifcopenshell-python/test/api/void/test_add_filling.py
@@ -0,0 +1,27 @@
+import test.bootstrap
+import ifcopenshell.api
+
+
+class TestAddFilling(test.bootstrap.IFC4):
+    def test_adding_a_filling(self):
+        opening = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcOpeningElement")
+        door = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcDoor")
+        ifcopenshell.api.run("void.add_filling", self.file, opening=opening, element=door)
+        assert door.FillsVoids[0].RelatingOpeningElement == opening
+
+    def test_adding_a_filling_twice(self):
+        opening = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcOpeningElement")
+        door = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcDoor")
+        ifcopenshell.api.run("void.add_filling", self.file, opening=opening, element=door)
+        ifcopenshell.api.run("void.add_filling", self.file, opening=opening, element=door)
+        assert door.FillsVoids[0].RelatingOpeningElement == opening
+        assert len(opening.HasFillings) == 1
+
+    def test_adding_a_filling_which_is_already_filling_another_opening(self):
+        door = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcDoor")
+        opening1 = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcOpeningElement")
+        opening2 = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcOpeningElement")
+        ifcopenshell.api.run("void.add_filling", self.file, opening=opening1, element=door)
+        ifcopenshell.api.run("void.add_filling", self.file, opening=opening2, element=door)
+        assert not opening1.HasFillings
+        assert opening2.HasFillings[0].RelatedBuildingElement == door