diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index ac98384..3d2c64d 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -3677,6 +3677,7 @@
 				block_end - cur_offset, 0);
 		if (IS_ERR(em)) {
 			err = PTR_ERR(em);
+			em = NULL;
 			break;
 		}
 		last_byte = min(extent_map_end(em), block_end);