--- /dev/null
+/*!\file sys/errno.h
+ *
+ * Compatibility header.
+ */
+
+/*
+ * The naming <sys/w??.h> is required for those compilers that
+ * have <sys/??.h> in the usual place but doesn't define stuff
+ * related to Watt-32's BSD-socket interface.
+ */
+
+#ifndef __SYS_WERRNO_H
+#include <sys/werrno.h>
+#endif
+