diff --git a/sys/kern/subr_localcount.c b/sys/kern/subr_localcount.c
index 064d5407f07..2948d24ed08 100644
--- a/sys/kern/subr_localcount.c
+++ b/sys/kern/subr_localcount.c
@@ -54,6 +54,9 @@ __KERNEL_RCSID(0, "$NetBSD: subr_localcount.c,v 1.6 2017/06/12 21:08:34 riastrad
 #include <sys/mutex.h>
 #include <sys/percpu.h>
 #include <sys/xcall.h>
+#if defined(DEBUG) && defined(LOCKDEBUG)
+#include <sys/atomic.h>
+#endif
 
 static void localcount_xc(void *, void *);
 
@@ -209,6 +212,10 @@ localcount_acquire(struct localcount *lc)
 
 	KASSERT(lc->lc_totalp == NULL);
 	localcount_adjust(lc, +1);
+#if defined(DEBUG) && defined(LOCKDEBUG)
+	if (atomic_inc_uint_nv(&lc->lc_refcnt) == 0)
+		panic("counter overflow");
+#endif
 }
 
 /*
@@ -253,5 +260,26 @@ localcount_release(struct localcount *lc, kcondvar_t *cv, kmutex_t *interlock)
 	}
 
 	localcount_adjust(lc, -1);
+#if defined(DEBUG) && defined(LOCKDEBUG)
+	if (atomic_dec_uint_nv(&lc->lc_refcnt) == UINT_MAX)
+		panic("counter underflow");
+#endif
  out:	kpreempt_enable();
 }
+
+/*
+ * localcount_debug_refcnt(lc)
+ *
+ *	Return a total reference count of lc.  It returns a correct value
+ *	only if DEBUG and LOCKDEBUG enabled.  Otherwise always return 0.
+ */
+uint32_t
+localcount_debug_refcnt(const struct localcount *lc)
+{
+
+#if defined(DEBUG) && defined(LOCKDEBUG)
+	return lc->lc_refcnt;
+#else
+	return 0;
+#endif
+}
diff --git a/sys/sys/localcount.h b/sys/sys/localcount.h
index 6a301197e95..e43a78bf80b 100644
--- a/sys/sys/localcount.h
+++ b/sys/sys/localcount.h
@@ -45,6 +45,7 @@ struct percpu;
 struct localcount {
 	int64_t		*lc_totalp;
 	struct percpu	*lc_percpu; /* int64_t */
+	uint32_t	lc_refcnt; /* only for debugging */
 };
 
 void	localcount_init(struct localcount *);
@@ -55,4 +56,7 @@ void	localcount_acquire(struct localcount *);
 void	localcount_release(struct localcount *, struct kcondvar *,
 	    struct kmutex *);
 
+uint32_t
+	localcount_debug_refcnt(const struct localcount *);
+
 #endif	/* _SYS_LOCALCOUNT_H */