diff --git a/kernel/kobject.c b/kernel/kobject.c
index 255cad7..7e89be8 100644
--- a/kernel/kobject.c
+++ b/kernel/kobject.c
@@ -75,6 +75,10 @@ struct kobject *kobject_create_pipe(struct pipe *p)
 	return k;
 }
 
+#ifdef KERNEL_KOBJECT_EXT
+  #include "kernel_kobject_ext.c"
+#endif
+
 struct kobject *kobject_addref(struct kobject *k)
 {
 	k->refcount++;
@@ -115,6 +119,9 @@ struct kobject * kobject_copy( struct kobject *ksrc )
 	case KOBJECT_PIPE:
 		pipe_addref(ksrc->data.pipe);
 		break;
+	default:
+	  /*ignore */
+	  break;
 	}
 
 	return kdst;
@@ -385,6 +392,9 @@ int kobject_size(struct kobject *kobject, int *dims, int n)
 		} else {
 			return KERROR_INVALID_REQUEST;
 		}
+  default:
+  	/* invalid */
+  	return KERROR_INVALID_REQUEST;
 	}
 	return KERROR_INVALID_REQUEST;
 }