diff --git a/src/ifcopenshell-python/ifcopenshell/api/sequence/calculate_task_duration.py b/src/ifcopenshell-python/ifcopenshell/api/sequence/calculate_task_duration.py
index b8b4d857b6..d5f0e5947e 100644
--- a/src/ifcopenshell-python/ifcopenshell/api/sequence/calculate_task_duration.py
+++ b/src/ifcopenshell-python/ifcopenshell/api/sequence/calculate_task_duration.py
@@ -143,5 +143,5 @@ class Usecase:
 
     def set_task_duration(self, duration: float) -> None:
         if not (task_time := self.task.TaskTime):
-            ifcopenshell.api.sequence.add_task_time(self.file, task=self.task)
+            task_time = ifcopenshell.api.sequence.add_task_time(self.file, task=self.task)
         task_time.ScheduleDuration = f"P{duration}D"
diff --git a/src/ifcopenshell-python/ifcopenshell/api/style/edit_surface_style.py b/src/ifcopenshell-python/ifcopenshell/api/style/edit_surface_style.py
index dba4dd48ea..7f7f05948d 100644
--- a/src/ifcopenshell-python/ifcopenshell/api/style/edit_surface_style.py
+++ b/src/ifcopenshell-python/ifcopenshell/api/style/edit_surface_style.py
@@ -76,7 +76,6 @@ def edit_surface_style(
 
 class Usecase:
     file: ifcopenshell.file
-    settings: dict[str, Any]
 
     def execute(self, style: ifcopenshell.entity_instance, attributes: dict[str, Any]) -> None:
         self.style = style
@@ -100,7 +99,7 @@ class Usecase:
             elif attribute_class == "IfcColourOrFactor":
                 self.edit_colour_or_factor(key, value)
             else:
-                setattr(self.settings["style"], key, value)
+                setattr(style, key, value)
 
     def edit_colour_rgb(self, name: str, value: dict[str, Any]):
         if (attribute := getattr(self.style, name)) is None:
diff --git a/src/ifcopenshell-python/ifcopenshell/api/unit/unassign_unit.py b/src/ifcopenshell-python/ifcopenshell/api/unit/unassign_unit.py
index 8e0335b77e..9651bfa87e 100644
--- a/src/ifcopenshell-python/ifcopenshell/api/unit/unassign_unit.py
+++ b/src/ifcopenshell-python/ifcopenshell/api/unit/unassign_unit.py
@@ -50,4 +50,5 @@ def unassign_unit(file: ifcopenshell.file, units: Optional[list[ifcopenshell.ent
     units_set = units_set - set(units or [])
     if units_set:
         unit_assignment.Units = list(units_set)
+        return
     file.remove(unit_assignment)
diff --git a/src/ifcopenshell-python/test/api/structural/test_edit_structural_analysis_model.py b/src/ifcopenshell-python/test/api/structural/test_edit_structural_analysis_model.py
index 18f389f488..fddb8a9993 100644
--- a/src/ifcopenshell-python/test/api/structural/test_edit_structural_analysis_model.py
+++ b/src/ifcopenshell-python/test/api/structural/test_edit_structural_analysis_model.py
@@ -23,7 +23,7 @@ import ifcopenshell.api.structural
 class TestEditStructuralAnalysisModel(test.bootstrap.IFC4):
     def test_editing_a_structural_analysis_model(self):
         subject = ifcopenshell.api.structural.add_structural_analysis_model(self.file)
-        subject = ifcopenshell.api.structural.edit_structural_analysis_model(
+        ifcopenshell.api.structural.edit_structural_analysis_model(
             self.file,
             structural_analysis_model=subject,
             attributes={"Name": "My edited model", "Description": "Description of my model"},