diff --git a/sys/sys/bus.h b/sys/sys/bus.h
--- a/sys/sys/bus.h
+++ b/sys/sys/bus.h
@@ -933,7 +933,7 @@
 static __inline type							\
 varp ## _get_ ## var(device_t dev)					\
 {									\
-	uintptr_t v;							\
+	uintptr_t v = 0;						\
 	int e __diagused;						\
 	e = BUS_READ_IVAR(device_get_parent(dev), dev,			\
 	    ivarp ## _IVAR_ ## ivar, &v);				\