diff a/Userland/Libraries/LibC/serenity.h b/Userland/Libraries/LibC/serenity.h	(rejected hunks)
@@ -55,10 +55,47 @@ int profiling_disable(pid_t);
 int set_thread_boost(pid_t tid, int amount);
 int set_process_boost(pid_t, int amount);
 
+#define _FUTEX_OP_SHIFT_OP 28
+#define _FUTEX_OP_MASK_OP 0xf
+#define _FUTEX_OP_SHIFT_CMP 24
+#define _FUTEX_OP_MASK_CMP 0xf
+#define _FUTEX_OP_SHIFT_OP_ARG 12
+#define _FUTEX_OP_MASK_OP_ARG 0xfff
+#define _FUTEX_OP_SHIFT_CMP_ARG 0
+#define _FUTEX_OP_MASK_CMP_ARG 0xfff
+
+#define FUTEX_OP(op, op_arg, cmp, cmp_arg) \
+    ((((op)&_FUTEX_OP_MASK_OP) << _FUTEX_OP_SHIFT_OP) | (((cmp)&_FUTEX_OP_MASK_CMP) << _FUTEX_OP_SHIFT_CMP) | (((op_arg)&_FUTEX_OP_MASK_OP_ARG) << _FUTEX_OP_SHIFT_OP_ARG) | (((cmp_arg)&_FUTEX_OP_MASK_CMP_ARG) << _FUTEX_OP_SHIFT_CMP_ARG))
+
+#define FUTEX_OP_SET 0
+#define FUTEX_OP_ADD 1
+#define FUTEX_OP_OR 2
+#define FUTEX_OP_ANDN 3
+#define FUTEX_OP_XOR 4
+#define FUTEX_OP_ARG_SHIFT 8
+
+#define FUTEX_OP_CMP_EQ 0
+#define FUTEX_OP_CMP_NE 1
+#define FUTEX_OP_CMP_LT 2
+#define FUTEX_OP_CMP_LE 3
+#define FUTEX_OP_CMP_GT 4
+#define FUTEX_OP_CMP_GE 5
+
 #define FUTEX_WAIT 1
 #define FUTEX_WAKE 2
+#define FUTEX_REQUEUE 3
+#define FUTEX_CMP_REQUEUE 4
+#define FUTEX_WAKE_OP 5
+#define FUTEX_WAIT_BITSET 9
+#define FUTEX_WAKE_BITSET 10
+
+#define FUTEX_PRIVATE_FLAG (1 << 7)
+#define FUTEX_CLOCK_REALTIME (1 << 8)
+#define FUTEX_CMD_MASK ~(FUTEX_PRIVATE_FLAG | FUTEX_CLOCK_REALTIME)
+
+#define FUTEX_BITSET_MATCH_ANY 0xffffffff
 
-int futex(int32_t* userspace_address, int futex_op, int32_t value, const struct timespec* timeout);
+int futex(uint32_t* userspace_address, int futex_op, uint32_t value, const struct timespec* timeout, uint32_t* userspace_address2, uint32_t value3);
 
 #define PURGE_ALL_VOLATILE 0x1
 #define PURGE_ALL_CLEAN_INODE 0x2