Index: uspace/lib/c/generic/private/futex.h
===================================================================
--- uspace/lib/c/generic/private/futex.h	(revision 25f6bddb8298e93b8b3c063cd5d4808e555c9d54)
+++ uspace/lib/c/generic/private/futex.h	(revision 15639eccad9c8be4e57a86cf372ff060b025baa3)
@@ -43,4 +43,5 @@
 #include <fibril.h>
 #include <abi/cap.h>
+#include <abi/synch.h>
 
 typedef struct futex {
@@ -147,6 +148,6 @@
 	}
 
-	return __SYSCALL2(SYS_WAITQ_SLEEP, (sysarg_t) futex->whandle,
-	    (sysarg_t) timeout);
+	return __SYSCALL3(SYS_WAITQ_SLEEP, (sysarg_t) futex->whandle,
+	    (sysarg_t) timeout, (sysarg_t) SYNCH_FLAGS_FUTEX);
 }