diff --git a/lib/librumpuser/rumpuser.c b/lib/librumpuser/rumpuser.c
index 7c41fe4af14a..231c6b8837cd 100644
--- a/lib/librumpuser/rumpuser.c
+++ b/lib/librumpuser/rumpuser.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: rumpuser.c,v 1.3 2010/04/21 11:16:41 pooka Exp $	*/
+/*	$NetBSD: rumpuser.c,v 1.4 2010/04/28 00:33:45 pooka Exp $	*/
 
 /*
  * Copyright (c) 2007-2010 Antti Kantee.  All Rights Reserved.
@@ -27,7 +27,7 @@
 
 #include <sys/cdefs.h>
 #if !defined(lint)
-__RCSID("$NetBSD: rumpuser.c,v 1.3 2010/04/21 11:16:41 pooka Exp $");
+__RCSID("$NetBSD: rumpuser.c,v 1.4 2010/04/28 00:33:45 pooka Exp $");
 #endif /* !lint */
 
 /* thank the maker for this */
@@ -46,6 +46,7 @@ __RCSID("$NetBSD: rumpuser.c,v 1.3 2010/04/21 11:16:41 pooka Exp $");
 
 #ifdef __NetBSD__
 #include <sys/disklabel.h>
+#include <sys/sysctl.h>
 #endif
 
 #include <assert.h>
@@ -589,3 +590,18 @@ rumpuser_kill(int64_t pid, int sig, int *error)
 	return -1;
 #endif
 }
+
+int
+rumpuser_getnhostcpu(void)
+{
+	int ncpu;
+	size_t sz = sizeof(ncpu);
+
+#ifdef __NetBSD__
+	if (sysctlbyname("hw.ncpu", &ncpu, &sz, NULL, 0) == -1)
+		return 1;
+	return ncpu;
+#else
+	return 1;
+#endif
+}
diff --git a/sys/rump/include/rump/rumpuser.h b/sys/rump/include/rump/rumpuser.h
index 1ae2006e9192..a0d3f3a0858c 100644
--- a/sys/rump/include/rump/rumpuser.h
+++ b/sys/rump/include/rump/rumpuser.h
@@ -1,4 +1,4 @@
-/*	$NetBSD: rumpuser.h,v 1.39 2010/04/21 11:13:29 pooka Exp $	*/
+/*	$NetBSD: rumpuser.h,v 1.40 2010/04/28 00:33:45 pooka Exp $	*/
 
 /*
  * Copyright (c) 2007 Antti Kantee.  All Rights Reserved.
@@ -109,6 +109,8 @@ int rumpuser_writewatchfile_wait(int, intptr_t *, int *);
 
 int rumpuser_dprintf(const char *, ...);
 
+int rumpuser_getnhostcpu(void);
+
 /* rumpuser_pth */
 void rumpuser_thrinit(kernel_lockfn, kernel_unlockfn, int);
 void rumpuser_biothread(void *);