diff --git a/pyproject.toml b/pyproject.toml
index 4d82418..02ae584 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -17,3 +17,6 @@ content-type = "text/markdown"
 [tool.scikit-build]
 cmake.version = ">=3.15"
 wheel.packages = ["sparsediffpy"]
+# Persistent build dir: avoids scikit-build-core's TemporaryDirectory, whose cleanup
+# intermittently fails on Windows CI with WinError 32 (lingering mspdbsrv/AV handle).
+build-dir = "build/{wheel_tag}"