Use -exec instead of xargs. Darwin xargs "just works" like usual.
@@ -54,5 +54,6 @@ sed -e "s|@PREFIX@|$PREFIX|;s|@PKG_NAME@|$PKG_NAME|;s|@PKG_VERSION@|$PKG_VERSION
# Normalize permissions
chmod -R 755 $PREFIX/bin $PREFIX/lib/libwcs.${libsuffix}
-find $PREFIX/include $PREFIX/lib/pkgconfig $PREFIX/share/man -type f \
- | xargs -I'{}' chmod 644 '{}'
+find $PREFIX/include $PREFIX/lib/pkgconfig $PREFIX/share/man \
+ -type f \
+ -exec chmod 644 '{}' \;
