diff --git a/fs/overlayfs/export.c b/fs/overlayfs/export.c
index e065a5b9a442..ac9c3ad04016 100644
--- a/fs/overlayfs/export.c
+++ b/fs/overlayfs/export.c
@@ -796,7 +796,7 @@ static struct ovl_fh *ovl_fid_to_fh(struct fid *fid, int buflen, int fh_type)
 		return ERR_PTR(-ENOMEM);
 
 	/* Copy unaligned inner fh into aligned buffer */
-	memcpy(&fh->fb, fid, buflen - OVL_FH_WIRE_OFFSET);
+	memcpy(fh->buf, fid, buflen - OVL_FH_WIRE_OFFSET);
 	return fh;
 }
 
diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index eee8f08d32b6..e74a610a117e 100644
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -108,7 +108,7 @@ struct ovl_fh {
 	u8 padding[3];	/* make sure fb.fid is 32bit aligned */
 	union {
 		struct ovl_fb fb;
-		u8 buf[0];
+		DECLARE_FLEX_ARRAY(u8, buf);
 	};
 } __packed;