diff --git a/Kernel/API/POSIX/unistd.h b/Kernel/API/POSIX/unistd.h
index 58d4294d23..0a1ffdfa7b 100644
--- a/Kernel/API/POSIX/unistd.h
+++ b/Kernel/API/POSIX/unistd.h
@@ -27,6 +27,7 @@ extern "C" {
 #define MS_BIND (1 << 3)
 #define MS_RDONLY (1 << 4)
 #define MS_REMOUNT (1 << 5)
+#define MS_WXALLOWED (1 << 6)
 
 enum {
     _SC_MONOTONIC_CLOCK,