diff --git a/src/ifcopenshell-python/ifcopenshell/api/material/unassign_material.py b/src/ifcopenshell-python/ifcopenshell/api/material/unassign_material.py
index b79318e984..93361eef66 100644
--- a/src/ifcopenshell-python/ifcopenshell/api/material/unassign_material.py
+++ b/src/ifcopenshell-python/ifcopenshell/api/material/unassign_material.py
@@ -58,6 +58,7 @@ class Usecase:
         if self.settings["product"].is_a("IfcTypeObject"):
             material = ifcopenshell.util.element.get_material(self.settings["product"])
             if material.is_a() in ["IfcMaterialLayerSet", "IfcMaterialProfileSet"]:
+                # Remove set usages
                 for inverse in self.file.get_inverse(material):
                     if self.file.schema == "IFC2X3":
                         if not inverse.is_a("IfcMaterialLayerSetUsage"):
@@ -76,7 +77,8 @@ class Usecase:
             if rel.is_a("IfcRelAssociatesMaterial"):
                 if rel.RelatingMaterial.is_a() in ["IfcMaterialLayerSetUsage", "IfcMaterialProfileSetUsage"]:
                     # Warning: this may leave the model in a non-compliant state.
-                    self.file.remove(rel.RelatingMaterial)
+                    if self.file.get_total_inverses(rel.RelatingMaterial) == 1 and len(rel.RelatedObjects) == 1:
+                        self.file.remove(rel.RelatingMaterial)
                 if len(rel.RelatedObjects) == 1:
                     self.file.remove(rel)
                     continue
diff --git a/src/ifcopenshell-python/test/api/material/test_unassign_material.py b/src/ifcopenshell-python/test/api/material/test_unassign_material.py
index 2e2db1946c..aea9e78ddf 100644
--- a/src/ifcopenshell-python/test/api/material/test_unassign_material.py
+++ b/src/ifcopenshell-python/test/api/material/test_unassign_material.py
@@ -25,7 +25,9 @@ class TestUnassignMaterial(test.bootstrap.IFC4):
     def test_unassign_single_material(self):
         element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
         material = ifcopenshell.api.run("material.add_material", self.file, name="CON01")
-        ifcopenshell.api.run("material.assign_material", self.file, product=element, type="IfcMaterial", material=material)
+        ifcopenshell.api.run(
+            "material.assign_material", self.file, product=element, type="IfcMaterial", material=material
+        )
         ifcopenshell.api.run("material.unassign_material", self.file, product=element)
         assert len(self.file.by_type("IfcRelAssociatesMaterial")) == 0
         assert len(self.file.by_type("IfcWall")) == 1
@@ -35,8 +37,12 @@ class TestUnassignMaterial(test.bootstrap.IFC4):
         element1 = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
         element2 = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
         material = ifcopenshell.api.run("material.add_material", self.file, name="CON01")
-        ifcopenshell.api.run("material.assign_material", self.file, product=element1, type="IfcMaterial", material=material)
-        ifcopenshell.api.run("material.assign_material", self.file, product=element2, type="IfcMaterial", material=material)
+        ifcopenshell.api.run(
+            "material.assign_material", self.file, product=element1, type="IfcMaterial", material=material
+        )
+        ifcopenshell.api.run(
+            "material.assign_material", self.file, product=element2, type="IfcMaterial", material=material
+        )
         ifcopenshell.api.run("material.unassign_material", self.file, product=element2)
         assert element1.HasAssociations
         assert not element2.HasAssociations
@@ -68,6 +74,34 @@ class TestUnassignMaterial(test.bootstrap.IFC4):
         assert len(self.file.by_type("IfcMaterialLayerSet")) == 1
         assert len(self.file.by_type("IfcMaterialLayerSetUsage")) == 0
 
+    def test_unassign_material_layer_set_usage_from_element_with_multiple_invalid_usages(self):
+        element_type = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWallType")
+        element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
+        element2 = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
+        ifcopenshell.api.run("type.assign_type", self.file, related_object=element, relating_type=element_type)
+        ifcopenshell.api.run("type.assign_type", self.file, related_object=element2, relating_type=element_type)
+        material = ifcopenshell.api.run("material.add_material", self.file, name="CON01")
+        ifcopenshell.api.run("material.assign_material", self.file, product=element_type, type="IfcMaterialLayerSet")
+        rel = ifcopenshell.api.run(
+            "material.assign_material", self.file, product=element, type="IfcMaterialLayerSetUsage"
+        )
+
+        # In some invalid IFCs from Revit, they reuse usages. Let's recreate this invalid scenario
+        rel.RelatedObjects = list(rel.RelatedObjects) + [element2]
+
+        ifcopenshell.api.run("material.unassign_material", self.file, product=element)
+
+        assert len(self.file.by_type("IfcRelAssociatesMaterial")) == 2
+        for rel in self.file.by_type("IfcRelAssociatesMaterial"):
+            assert rel.RelatingMaterial
+        assert element_type.HasAssociations
+        assert len(self.file.by_type("IfcWallType")) == 1
+        assert len(self.file.by_type("IfcWall")) == 2
+        assert len(self.file.by_type("IfcMaterialLayerSet")) == 1
+        assert len(self.file.by_type("IfcMaterialLayerSetUsage")) == 1
+        assert ifcopenshell.util.element.get_material(element, should_inherit=False) is None
+        assert ifcopenshell.util.element.get_material(element2, should_inherit=False).is_a("IfcMaterialLayerSetUsage")
+
     def test_unassign_material_profile_set_from_type(self):
         element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWallType")
         material = ifcopenshell.api.run("material.add_material", self.file, name="CON01")
@@ -104,7 +138,9 @@ class TestUnassignMaterial(test.bootstrap.IFC4):
     def test_unassign_element_material_list(self):
         element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
         material = ifcopenshell.api.run("material.add_material", self.file, name="CON01")
-        ifcopenshell.api.run("material.assign_material", self.file, product=element, type="IfcMaterialList", material=material)
+        ifcopenshell.api.run(
+            "material.assign_material", self.file, product=element, type="IfcMaterialList", material=material
+        )
         ifcopenshell.api.run("material.unassign_material", self.file, product=element)
         assert len(self.file.by_type("IfcRelAssociatesMaterial")) == 0
         assert len(self.file.by_type("IfcMaterialList")) == 1