diff --git a/src/blenderbim/blenderbim/core/patch.py b/src/blenderbim/blenderbim/core/patch.py
index 2449d6250e..19571437c3 100644
--- a/src/blenderbim/blenderbim/core/patch.py
+++ b/src/blenderbim/blenderbim/core/patch.py
@@ -17,5 +17,14 @@
 # along with BlenderBIM Add-on.  If not, see <http://www.gnu.org/licenses/>.
 
 
-def run_migrate_patch(patch, infile=None, outfile=None, schema=None):
+from __future__ import annotations
+from typing import TYPE_CHECKING, Optional
+
+if TYPE_CHECKING:
+    import bpy
+    import ifcopenshell
+    import blenderbim.tool as tool
+
+
+def run_migrate_patch(patch: tool.Patch, infile: str, outfile: str, schema: str) -> None:
     patch.run_migrate_patch(infile, outfile, schema)
diff --git a/src/blenderbim/blenderbim/tool/patch.py b/src/blenderbim/blenderbim/tool/patch.py
index beb348eb0b..f543a98c6a 100644
--- a/src/blenderbim/blenderbim/tool/patch.py
+++ b/src/blenderbim/blenderbim/tool/patch.py
@@ -19,15 +19,22 @@
 import bpy
 import ifcopenshell
 import blenderbim.core.tool
+from typing import TYPE_CHECKING
+
 
 try:
     import ifcpatch
-except:
+except ImportError:
     print("IfcPatch not available")
 
+if TYPE_CHECKING:
+    import ifcpatch
+
 
 class Patch(blenderbim.core.tool.Patch):
     @classmethod
-    def run_migrate_patch(cls, infile, outfile, schema):
-        output = ifcpatch.execute({"input": infile, "file": ifcopenshell.open(infile), "recipe": "Migrate", "arguments": [schema]})
+    def run_migrate_patch(cls, infile: str, outfile: str, schema: str) -> None:
+        output = ifcpatch.execute(
+            {"input": infile, "file": ifcopenshell.open(infile), "recipe": "Migrate", "arguments": [schema]}
+        )
         ifcpatch.write(output, outfile)