diff --git a/src/blenderbim/blenderbim/bim/module/model/opening.py b/src/blenderbim/blenderbim/bim/module/model/opening.py
index b98c264336..f37243c40c 100644
--- a/src/blenderbim/blenderbim/bim/module/model/opening.py
+++ b/src/blenderbim/blenderbim/bim/module/model/opening.py
@@ -668,17 +668,17 @@ class RemoveBooleans(Operator, tool.Ifc.Operator, AddObjectHelper):
             except:
                 continue
 
-            boolean = None
+            boolean_id = None
             for inverse in tool.Ifc.get().get_inverse(item):
                 if inverse.is_a("IfcBooleanResult"):
-                    boolean = inverse
+                    boolean_id = inverse.id()
                     break
             ifcopenshell.api.run("geometry.remove_boolean", tool.Ifc.get(), item=item)
 
             if obj.data.BIMMeshProperties.obj:
                 upstream_obj = obj.data.BIMMeshProperties.obj
                 element = tool.Ifc.get_entity(upstream_obj)
-                bbim_boolean_updates.setdefault(element, []).append(boolean)
+                bbim_boolean_updates.setdefault(element, []).append(boolean_id)
                 body = ifcopenshell.util.representation.get_representation(element, "Model", "Body", "MODEL_VIEW")
                 if body:
                     blenderbim.core.geometry.switch_representation(
@@ -692,8 +692,8 @@ class RemoveBooleans(Operator, tool.Ifc.Operator, AddObjectHelper):
                     )
             bpy.data.objects.remove(obj)
 
-        for element, booleans in bbim_boolean_updates.items():
-            tool.Model.unmark_manual_booleans(element, booleans)
+        for element, boolean_ids in bbim_boolean_updates.items():
+            tool.Model.unmark_manual_booleans(element, boolean_ids)
 
         tool.Blender.set_active_object(upstream_obj)
         return {"FINISHED"}
diff --git a/src/blenderbim/blenderbim/bim/module/void/operator.py b/src/blenderbim/blenderbim/bim/module/void/operator.py
index 815389c73f..5914049d02 100644
--- a/src/blenderbim/blenderbim/bim/module/void/operator.py
+++ b/src/blenderbim/blenderbim/bim/module/void/operator.py
@@ -259,8 +259,10 @@ class BooleansMarkAsManual(bpy.types.Operator):
         if self.mark_as_manual:
             tool.Model.mark_manual_booleans(element, booleans)
         else:
-            tool.Model.unmark_manual_booleans(element, booleans)
+            tool.Model.unmark_manual_booleans(element, [b.id() for b in booleans])
 
-        self.report({"INFO"}, f"{len(booleans)} were marked as {'manual' if self.mark_as_manual else 'automatic'}")
+        self.report(
+            {"INFO"}, f"{len(booleans)} booleans were marked as {'manual' if self.mark_as_manual else 'automatic'}"
+        )
         blenderbim.bim.handler.refresh_ui_data()
         return {"FINISHED"}
diff --git a/src/blenderbim/blenderbim/tool/model.py b/src/blenderbim/blenderbim/tool/model.py
index 038b245c71..8d36618305 100644
--- a/src/blenderbim/blenderbim/tool/model.py
+++ b/src/blenderbim/blenderbim/tool/model.py
@@ -521,11 +521,12 @@ class Model(blenderbim.core.tool.Model):
         ifcopenshell.api.run("pset.edit_pset", tool.Ifc.get(), pset=pset, properties={"Data": data})
 
     @classmethod
-    def unmark_manual_booleans(cls, element, booleans):
+    def unmark_manual_booleans(cls, element, boolean_ids):
+        # NOTE: we use use boolean_ids instead of boolean entities
+        # so it will be possible to unmark manual booleans after they already was deleted
         pset = ifcopenshell.util.element.get_pset(element, "BBIM_Boolean")
         if not pset:
             return
-        boolean_ids = [b.id() for b in booleans]
         data = set(json.loads(pset["Data"]))
         data -= set(boolean_ids)
         data = list(data)
diff --git a/src/blenderbim/test/tool/test_model.py b/src/blenderbim/test/tool/test_model.py
index 1a7f914ff3..96f310da11 100644
--- a/src/blenderbim/test/tool/test_model.py
+++ b/src/blenderbim/test/tool/test_model.py
@@ -21,6 +21,7 @@ import ifcopenshell
 import blenderbim.core.tool
 import blenderbim.tool as tool
 import numpy as np
+import json
 from test.bim.bootstrap import NewFile
 from blenderbim.tool.model import Model as subject
 from ifcopenshell.util.shape_builder import V
@@ -108,6 +109,37 @@ class TestGetManualBooleans(NewFile):
         assert len(subject.get_manual_booleans(element)) == 2
 
 
+class TestMarkManualBooleans(NewFile):
+    def test_run(self):
+        ifc = ifcopenshell.file()
+        tool.Ifc.set(ifc)
+
+        element = ifc.createIfcWall()
+        boolean = ifc.createIfcBooleanClippingResult()
+        subject.mark_manual_booleans(element, [boolean])
+        pset = ifcopenshell.util.element.get_pset(element, "BBIM_Boolean")
+        assert pset
+        value = json.loads(pset["Data"])
+        assert set(value) == {boolean.id()}
+
+
+class TestUnmarkManualBooleans(NewFile):
+    def test_run(self):
+        ifc = ifcopenshell.file()
+        tool.Ifc.set(ifc)
+
+        element = ifc.createIfcWall()
+        boolean = ifc.createIfcBooleanClippingResult()
+        boolean2 = ifc.createIfcBooleanClippingResult()
+        subject.mark_manual_booleans(element, [boolean, boolean2])
+        subject.unmark_manual_booleans(element, [boolean.id()])
+
+        pset = ifcopenshell.util.element.get_pset(element, "BBIM_Boolean")
+        assert pset
+        value = json.loads(pset["Data"])
+        assert set(value) == {boolean2.id()}
+
+
 class TestStairCalculatedParams(NewFile):
     def compare_data(self, pset_data, expected_calculated_data):
         calculated_data = subject.get_active_stair_calculated_params(pset_data)