diff -Nurp VirtualBox-5.1.0.p2/src/VBox/Runtime/r3/linux/semmutex-linux.cpp VirtualBox-5.1.0.p3/src/VBox/Runtime/r3/linux/semmutex-linux.cpp
--- VirtualBox-5.1.0.p2/src/VBox/Runtime/r3/linux/semmutex-linux.cpp	2016-07-12 17:54:59.000000000 +0300
+++ VirtualBox-5.1.0.p3/src/VBox/Runtime/r3/linux/semmutex-linux.cpp	2016-07-13 00:53:18.421090025 +0300
@@ -89,7 +89,7 @@ struct RTSEMMUTEXINTERNAL
 static long sys_futex(int32_t volatile *uaddr, int op, int val, struct timespec *utime, int32_t *uaddr2, int val3)
 {
     errno = 0;
-    long rc = syscall(__NR_futex, uaddr, op, val, utime, uaddr2, val3);
+    long rc = syscall(SYS_futex, uaddr, op, val, utime, uaddr2, val3);
     if (rc < 0)
     {
         Assert(rc == -1);