diff --git a/src/bonsai/bonsai/bim/module/model/product.py b/src/bonsai/bonsai/bim/module/model/product.py
index 49f0bde998..5bfa2e66f6 100644
--- a/src/bonsai/bonsai/bim/module/model/product.py
+++ b/src/bonsai/bonsai/bim/module/model/product.py
@@ -19,7 +19,6 @@
 import bpy
 import mathutils
 import numpy as np
-from functools import reduce
 import ifcopenshell
 import ifcopenshell.api
 import ifcopenshell.util.system
diff --git a/src/bonsai/bonsai/core/drawing.py b/src/bonsai/bonsai/core/drawing.py
index 4afb45c4e9..57ab21dbe7 100644
--- a/src/bonsai/bonsai/core/drawing.py
+++ b/src/bonsai/bonsai/core/drawing.py
@@ -76,7 +76,7 @@ def disable_editing_sheets(drawing: tool.Drawing) -> None:
     drawing.disable_editing_sheets()
 
 
-def add_sheet(ifc: tool.Ifc, drawing, titleblock: ifcopenshell.entity_instance) -> None:
+def add_sheet(ifc: tool.Ifc, drawing: tool.Drawing, titleblock: ifcopenshell.entity_instance) -> None:
     sheet = ifc.run("document.add_information")
     layout = ifc.run("document.add_reference", information=sheet)
     titleblock_reference = ifc.run("document.add_reference", information=sheet)
@@ -127,7 +127,9 @@ def remove_sheet(ifc: tool.Ifc, drawing: tool.Drawing, sheet: ifcopenshell.entit
     drawing.import_sheets()
 
 
-def rename_sheet(ifc: tool.Ifc, drawing, sheet: ifcopenshell.entity_instance, identification: str, name: str) -> None:
+def rename_sheet(
+    ifc: tool.Ifc, drawing: tool.Drawing, sheet: ifcopenshell.entity_instance, identification: str, name: str
+) -> None:
     if ifc.get_schema() == "IFC2X3":
         attributes = {"DocumentId": identification, "Name": name}
     else:
diff --git a/src/bonsai/bonsai/tool/ifc.py b/src/bonsai/bonsai/tool/ifc.py
index 3efad2bfa6..57c81b84cf 100644
--- a/src/bonsai/bonsai/tool/ifc.py
+++ b/src/bonsai/bonsai/tool/ifc.py
@@ -22,6 +22,7 @@ import numpy as np
 import ifcopenshell.api
 import ifcopenshell.ifcopenshell_wrapper as ifcopenshell_wrapper
 import ifcopenshell.util.element
+import ifcopenshell.util.schema
 import bonsai.core.tool
 import bonsai.bim.handler
 import bonsai.tool as tool
@@ -60,7 +61,7 @@ class Ifc(bonsai.core.tool.Ifc):
         return IfcStore.path
 
     @classmethod
-    def get_schema(cls) -> str:
+    def get_schema(cls) -> ifcopenshell.util.schema.IFC_SCHEMA:
         if IfcStore.get_file():
             return IfcStore.get_file().schema
 
diff --git a/src/ifcopenshell-python/ifcopenshell/file.py b/src/ifcopenshell-python/ifcopenshell/file.py
index addca6a3be..0a6bbc8594 100644
--- a/src/ifcopenshell-python/ifcopenshell/file.py
+++ b/src/ifcopenshell-python/ifcopenshell/file.py
@@ -24,11 +24,14 @@ import zipfile
 import functools
 import ifcopenshell
 from pathlib import Path
-from typing import Optional, Any, Union, Callable, Generator, Literal
+from typing import Optional, Any, Union, Callable, Generator, Literal, TYPE_CHECKING
 
 from . import ifcopenshell_wrapper
 from .entity_instance import entity_instance
 
+if TYPE_CHECKING:
+    import ifcopenshell.util.schema
+
 
 class Transaction:
     def __init__(self, ifc_file):
@@ -406,7 +409,7 @@ class file:
         return e
 
     @property
-    def schema(self) -> Literal["IFC2X3", "IFC4", "IFC4X3"]:
+    def schema(self) -> ifcopenshell.util.schema.IFC_SCHEMA:
         """General IFC schema version: IFC2X3, IFC4, IFC4X3."""
         prefixes = ("IFC", "X", "_ADD", "_TC")
         reg = "".join(f"(?P<{s}>{s}\\d+)?" for s in prefixes)
diff --git a/src/ifcopenshell-python/ifcopenshell/util/doc.py b/src/ifcopenshell-python/ifcopenshell/util/doc.py
index 2753d7d63b..b444966068 100644
--- a/src/ifcopenshell-python/ifcopenshell/util/doc.py
+++ b/src/ifcopenshell-python/ifcopenshell/util/doc.py
@@ -60,7 +60,7 @@ IFC4x3_SPEC_URL_TEMPLATE = "https://ifc43-docs.standards.buildingsmart.org/IFC/R
 # child -> description
 # note: in IFC4x3 there is no children[] for properties
 
-SUPPORTED_SCHEMA = Literal["IFC2X3", "IFC4", "IFC4X3"]
+SUPPORTED_SCHEMA = ifcopenshell.util.schema.IFC_SCHEMA
 SCHEMA_FILES: dict[SUPPORTED_SCHEMA, dict] = {
     "IFC2X3": {
         "entities": BASE_MODULE_PATH / "schema/ifc2x3_entities.json",
diff --git a/src/ifcopenshell-python/ifcopenshell/util/schema.py b/src/ifcopenshell-python/ifcopenshell/util/schema.py
index fe08240d07..3a2021b8ef 100644
--- a/src/ifcopenshell-python/ifcopenshell/util/schema.py
+++ b/src/ifcopenshell-python/ifcopenshell/util/schema.py
@@ -22,11 +22,12 @@ import time
 import ifcopenshell
 import ifcopenshell.util.attribute
 import ifcopenshell.ifcopenshell_wrapper as ifcopenshell_wrapper
-from typing import Union, Any
+from typing import Union, Any, Literal
 
 # This is highly experimental and incomplete, however, it may work for simple datasets.
 
 cwd = os.path.dirname(os.path.realpath(__file__))
+IFC_SCHEMA = Literal["IFC2X3", "IFC4", "IFC4X3"]
 
 
 def get_fallback_schema(version: str) -> str:
diff --git a/src/ifcopenshell-python/ifcopenshell/util/type.py b/src/ifcopenshell-python/ifcopenshell/util/type.py
index 3cd2750d2b..bfb0f40bc0 100644
--- a/src/ifcopenshell-python/ifcopenshell/util/type.py
+++ b/src/ifcopenshell-python/ifcopenshell/util/type.py
@@ -23,8 +23,8 @@ from typing import List
 
 cwd = os.path.dirname(os.path.realpath(__file__))
 
-entity_to_type_map = {}
-type_to_entity_map = {}
+entity_to_type_map: dict[ifcopenshell.util.schema.IFC_SCHEMA, dict[str, list[str]]] = {}
+type_to_entity_map: dict[ifcopenshell.util.schema.IFC_SCHEMA, dict[str, list[str]]] = {}
 
 mapped_schemas = {
     "IFC2X3": "entity_to_type_map_2x3.json",
diff --git a/src/ifcpatch/ifcpatch/recipes/Migrate.py b/src/ifcpatch/ifcpatch/recipes/Migrate.py
index 4b3a1cf8c9..9938ddd754 100644
--- a/src/ifcpatch/ifcpatch/recipes/Migrate.py
+++ b/src/ifcpatch/ifcpatch/recipes/Migrate.py
@@ -28,7 +28,7 @@ class Patcher:
         src: str,
         file: ifcopenshell.file,
         logger: Logger,
-        schema: typing.Literal["IFC2X3", "IFC4", "IFC4X3"] = "IFC4",
+        schema: ifcopenshell.util.schema.IFC_SCHEMA = "IFC4",
     ):
         """Migrate from one IFC version to another