diff --git a/setup.py b/setup.py
index 5b79e389..3714e9e3 100644
--- a/setup.py
+++ b/setup.py
@@ -451,7 +451,7 @@ def _classify_installed_files_override(
             data_files,
             # To get around a check that prepends source dir to paths and breaks package detection code.
             cmake_source_dir="",
-            cmake_install_dir=cmake_install_reldir,
+            _cmake_install_dir=cmake_install_reldir,
         )