1 files changed, 5 insertions, 0 deletions
diff --git a/regexp.h b/regexp.h
index 94492f5..ee4ae29 100644
--- a/regexp.h
+++ b/regexp.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 && _XOPEN_SOURCE < 600)
 /* ./src/regexp/loc1.c */
 extern char *loc1;