1 files changed, 5 insertions, 0 deletions

diff --git a/ucontext.h b/ucontext.h
index 515aaec..a8e4531 100644
--- a/ucontext.h
+++ b/ucontext.h
@@ -27,6 +27,11 @@ OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 SOFTWARE.
 */
 
+#if defined _XOPEN_SOURCE && _XOPEN_SOURCE - 1 < 0
+#undef _XOPEN_SOURCE
+#define _XOPEN_SOURCE 400
+#endif
+
 #if defined _XOPEN_SOURCE && !defined _POSIX_C_SOURCE
 #	if (_XOPEN_SOURCE >= 700)
 #		define _POSIX_C_SOURCE 200809L