diff --git a/pyproject.toml b/pyproject.toml
index 7ac4f8265f..d3e51e1ed7 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -220,6 +220,7 @@ cmake-format = "gersemi . --in-place"
 cmd = """
     ty check
     nix/
+    win/
     src/bcf
     src/bsdd
     src/ifc2ca
diff --git a/win/run-cmake.py b/win/run-cmake.py
index df09a9e032..4691178863 100644
--- a/win/run-cmake.py
+++ b/win/run-cmake.py
@@ -293,7 +293,7 @@ def main() -> None:
 
     cmake_prefix_path_parts = Deps.cmake_prefix_paths()
     if qt_dir:
-        cmake_prefix_path_parts.append(qt_dir)
+        cmake_prefix_path_parts.append(Path(qt_dir))
     cmake_prefix_path = ";".join(str(part) for part in cmake_prefix_path_parts)
 
     if ARGS.use_ninja: