diff --git a/sys/kern/kern_lock.c b/sys/kern/kern_lock.c
--- a/sys/kern/kern_lock.c
+++ b/sys/kern/kern_lock.c
@@ -37,6 +37,7 @@
 #include <sys/param.h>
 #include <sys/kdb.h>
 #include <sys/ktr.h>
+#include <sys/limits.h>
 #include <sys/lock.h>
 #include <sys/lock_profile.h>
 #include <sys/lockmgr.h>
@@ -61,6 +62,12 @@
 PMC_SOFT_DECLARE( , , lock, failed);
 #endif
 
+/*
+ * Hack. There should be prio_t or similar so that this is not necessary.
+ */
+_Static_assert((PRILASTFLAG * 2) - 1 <= USHRT_MAX,
+    "prio flags wont fit in u_short pri in struct lock");
+
 CTASSERT(LK_UNLOCKED == (LK_UNLOCKED &
     ~(LK_ALL_WAITERS | LK_EXCLUSIVE_SPINNERS)));
 
@@ -280,8 +287,10 @@
 
 	if (flags & LK_INTERLOCK)
 		class->lc_unlock(ilk);
-	if (queue == SQ_EXCLUSIVE_QUEUE && (flags & LK_SLEEPFAIL) != 0)
-		lk->lk_exslpfail++;
+	if (queue == SQ_EXCLUSIVE_QUEUE && (flags & LK_SLEEPFAIL) != 0) {
+		if (lk->lk_exslpfail < USHRT_MAX)
+			lk->lk_exslpfail++;
+	}
 	GIANT_SAVE();
 	sleepq_add(&lk->lock_object, NULL, wmesg, SLEEPQ_LK | (catch ?
 	    SLEEPQ_INTERRUPTIBLE : 0), queue);
@@ -345,7 +354,7 @@
 		realexslp = sleepq_sleepcnt(&lk->lock_object,
 		    SQ_EXCLUSIVE_QUEUE);
 		if ((x & LK_EXCLUSIVE_WAITERS) != 0 && realexslp != 0) {
-			if (lk->lk_exslpfail < realexslp) {
+			if (lk->lk_exslpfail != USHRT_MAX && lk->lk_exslpfail < realexslp) {
 				lk->lk_exslpfail = 0;
 				queue = SQ_EXCLUSIVE_QUEUE;
 				v |= (x & LK_SHARED_WAITERS);
@@ -362,7 +371,6 @@
 				    SLEEPQ_LK, 0, SQ_EXCLUSIVE_QUEUE);
 				queue = SQ_SHARED_QUEUE;
 			}
-				
 		} else {
 			/*
 			 * Exclusive waiters sleeping with LK_SLEEPFAIL on
@@ -1170,7 +1178,7 @@
 	MPASS((x & LK_EXCLUSIVE_SPINNERS) == 0);
 	realexslp = sleepq_sleepcnt(&lk->lock_object, SQ_EXCLUSIVE_QUEUE);
 	if ((x & LK_EXCLUSIVE_WAITERS) != 0 && realexslp != 0) {
-		if (lk->lk_exslpfail < realexslp) {
+		if (lk->lk_exslpfail != USHRT_MAX && lk->lk_exslpfail < realexslp) {
 			lk->lk_exslpfail = 0;
 			queue = SQ_EXCLUSIVE_QUEUE;
 			v |= (x & LK_SHARED_WAITERS);
diff --git a/sys/kern/subr_lock.c b/sys/kern/subr_lock.c
--- a/sys/kern/subr_lock.c
+++ b/sys/kern/subr_lock.c
@@ -40,6 +40,7 @@
 #include <sys/systm.h>
 #include <sys/kernel.h>
 #include <sys/ktr.h>
+#include <sys/limits.h>
 #include <sys/lock.h>
 #include <sys/lock_profile.h>
 #include <sys/malloc.h>
diff --git a/sys/sys/_lockmgr.h b/sys/sys/_lockmgr.h
--- a/sys/sys/_lockmgr.h
+++ b/sys/sys/_lockmgr.h
@@ -40,9 +40,9 @@
 struct lock {
 	struct lock_object	lock_object;
 	volatile uintptr_t	lk_lock;
-	u_int			lk_exslpfail;
+	u_short			lk_exslpfail;
+	u_short			lk_pri;
 	int			lk_timo;
-	int			lk_pri;
 #ifdef DEBUG_LOCKS
 	struct stack		lk_stack;
 #endif
diff --git a/sys/sys/param.h b/sys/sys/param.h
--- a/sys/sys/param.h
+++ b/sys/sys/param.h
@@ -227,9 +227,10 @@
 	((off_t)(db) << DEV_BSHIFT)
 #endif
 
-#define	PRIMASK	0x0ff
-#define	PCATCH	0x100		/* OR'd with pri for tsleep to check signals */
-#define	PDROP	0x200	/* OR'd with pri to stop re-entry of interlock mutex */
+#define	PRIMASK		0x0ff
+#define	PCATCH		0x100	/* OR'd with pri for tsleep to check signals */
+#define	PDROP		0x200	/* OR'd with pri to stop re-entry of interlock mutex */
+#define	PRILASTFLAG	0x200	/* Last flag defined above */
 
 #define	NZERO	0		/* default "nice" */