diff --git a/server/mailslot.c b/server/mailslot.c
index 4066e57e817..09000e64c83 100644
--- a/server/mailslot.c
+++ b/server/mailslot.c
@@ -39,7 +39,9 @@
 #ifdef HAVE_SYS_SOCKET_H
 #include <sys/socket.h>
 #endif
-
+#ifdef HAVE_SYS_FILIO_H
+#include <sys/filio.h>
+#endif
 #include "windef.h"
 #include "winbase.h"