diff --git a/sys/kern/bus_if.m b/sys/kern/bus_if.m
index 688a47010e8b..de808ded6386 100644
--- a/sys/kern/bus_if.m
+++ b/sys/kern/bus_if.m
@@ -26,6 +26,8 @@
 # $FreeBSD$
 #
 
+#include <sys/types.h>
+#include <sys/systm.h>
 #include <sys/bus.h>
 
 /**
@@ -56,6 +58,14 @@ CODE {
 			return (BUS_REMAP_INTR(dev, NULL, irq));
 		return (ENXIO);
 	}
+
+	static device_t
+	null_add_child(device_t bus, int order, const char *name,
+	    int unit)
+	{
+
+		panic("bus_add_child is not implemented");
+	}
 };
 
 /**
@@ -203,7 +213,7 @@ METHOD device_t add_child {
 	u_int _order;
 	const char *_name;
 	int _unit;
-};
+} DEFAULT null_add_child;
 
 /**
  * @brief Allocate a system resource