diff --git a/include/linux/cgroup-defs.h b/include/linux/cgroup-defs.h
index 7d83d7f..26d1cea 100644
--- a/include/linux/cgroup-defs.h
+++ b/include/linux/cgroup-defs.h
@@ -26,6 +26,7 @@
 struct kernfs_node;
 struct kernfs_ops;
 struct kernfs_open_file;
+struct seq_file;
 
 #define MAX_CGROUP_TYPE_NAMELEN 32
 #define MAX_CGROUP_ROOT_NAMELEN 64