diff --git a/quota.h b/quota.h
index ac034d0..9c37bed 100644
--- a/quota.h
+++ b/quota.h
@@ -145,6 +145,7 @@ enum {
 #define QFMT_VFS_V0  2
 #define QFMT_OCFS2   3
 #define QFMT_VFS_V1  4
+#define QFMT_NS      5
 
 /* Flags supported by kernel */
 #define V1_DQF_RSQUASH 1