diff --git a/lib/portage/package/ebuild/prepare_build_dirs.py b/lib/portage/package/ebuild/prepare_build_dirs.py
index 2e2ef73..f37c964 100644
--- a/lib/portage/package/ebuild/prepare_build_dirs.py
+++ b/lib/portage/package/ebuild/prepare_build_dirs.py
@@ -483,9 +483,9 @@
     portage.util.ensure_dirs(filesdir, mode=0o755)
 
     # Copy files from real directory to ebuild directory (without metadata).
-    if os.path.isdir(real_filesdir):
+    if os.path.isdir(real_filesdir) and not os.path.isdir(filesdir):
         shutil.copytree(
-            real_filesdir, filesdir, copy_function=copyfile, dirs_exist_ok=True
+            real_filesdir, filesdir, copy_function=copyfile
         )