diff --git a/rtree/finder.py b/rtree/finder.py
index f852e813..e03d2127 100644
--- a/rtree/finder.py
+++ b/rtree/finder.py
@@ -143,7 +143,7 @@ def get_include() -> str:
         if pkg_files is not None:
             for path in pkg_files:  # type: ignore
                 if path.name == "SpatialIndex.h":
-                    return str(path.parent.parent)
+                    return str(Path(path.locate()).parent.parent)
     except importlib.metadata.PackageNotFoundError:
         pass
 
diff --git a/setup.py b/setup.py
index db474146..a1fc40d9 100755
--- a/setup.py
+++ b/setup.py
@@ -56,15 +56,12 @@ def finalize_options(self) -> None:
             else:
                 raise ValueError(f"unhandled platform {sys.platform!r}")
 
+            target_lib.mkdir(parents=True, exist_ok=True)
             for pth in source_lib.glob(lib_pattern):
                 # if the source isn't a file skip it
                 if not pth.is_file():
                     continue
 
-                # make directory if it doesn't exist yet
-                if not target_lib.is_dir():
-                    target_lib.mkdir(parents=True)
-
                 # copy the source file to the target directory
                 self.copy_file(str(pth), str(target_lib / pth.name))
 
@@ -73,14 +70,11 @@ def finalize_options(self) -> None:
         if source_include.is_dir():
             for pth in source_include.rglob("*.h"):
                 rpth = pth.relative_to(source_include)
-                target_subdir = target_include / rpth
-
-                # make directory if it doesn't exist yet
-                if not target_subdir.is_dir():
-                    target_subdir.mkdir(parents=True)
 
                 # copy the source file to the target directory
-                self.copy_file(str(pth), str(target_include / rpth))
+                target_subdir = target_include / rpth.parent
+                target_subdir.mkdir(parents=True, exist_ok=True)
+                self.copy_file(str(pth), str(target_subdir))
 
 
 # See pyproject.toml for other project metadata