Index: /trunk/src/VBox/Runtime/r3/posix/fileio-posix.cpp
===================================================================
--- /trunk/src/VBox/Runtime/r3/posix/fileio-posix.cpp	(revision 24000)
+++ /trunk/src/VBox/Runtime/r3/posix/fileio-posix.cpp	(revision 24001)
@@ -234,5 +234,5 @@
 # elif defined(RT_OS_DARWIN)
             if (fOpen & RTFILE_O_NO_CACHE)
-                iErr = fcntl(fh, F_NOCACHE);
+                iErr = fcntl(fh, F_NOCACHE, 1);
 # endif
             if (iErr < 0)