diff --git a/build.py b/build.py
index 5c1e6d3..0670879 100644
--- a/build.py
+++ b/build.py
@@ -523,7 +523,7 @@
     cp "${BUILD_DIR}/Foundation/Foundation.swiftmodule" "${DSTROOT}/${PREFIX}/lib/swift/${OS}/${ARCH}/"; $
     cp "${BUILD_DIR}/Foundation/Foundation.swiftdoc" "${DSTROOT}/${PREFIX}/lib/swift/${OS}/${ARCH}/"; $
     mkdir -p "${DSTROOT}/${PREFIX}/local/include"; $
-    rsync -r "${BUILD_DIR}/Foundation/${PREFIX}/lib/swift/CoreFoundation" "${DSTROOT}/${PREFIX}/lib/swift/"
+    rsync -a "${BUILD_DIR}/Foundation/${PREFIX}/lib/swift/CoreFoundation" "${DSTROOT}/${PREFIX}/lib/swift/"
 
 build ${BUILD_DIR}/.install: InstallFoundation ${BUILD_DIR}/Foundation/${DYLIB_PREFIX}Foundation${DYLIB_SUFFIX}