diff --git a/kernel/sys.c b/kernel/sys.c
index ec319bb..df4c3a8 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -14,6 +14,7 @@
 #include <linux/prctl.h>
 #include <linux/highuid.h>
 #include <linux/fs.h>
+#include <linux/resource.h>
 #include <linux/kernel.h>
 #include <linux/kexec.h>
 #include <linux/workqueue.h>
@@ -659,7 +660,7 @@
 	int error = -EINVAL;
 	struct pid *pgrp;
 
-	if (which > 2 || which < 0)
+	if (which > PRIO_USER || which < PRIO_PROCESS)
 		goto out;
 
 	/* normalize: avoid signed division (rounding problems) */
@@ -723,7 +724,7 @@
 	long niceval, retval = -ESRCH;
 	struct pid *pgrp;
 
-	if (which > 2 || which < 0)
+	if (which > PRIO_USER || which < PRIO_PROCESS)
 		return -EINVAL;
 
 	read_lock(&tasklist_lock);