diff --git a/bzip_extent_writer.h b/bzip_extent_writer.h
index 9726253..0187c0b 100644
--- a/bzip_extent_writer.h
+++ b/bzip_extent_writer.h
@@ -23,7 +23,9 @@
   }
   ~BzipExtentWriter() {}
 
-  bool Init(int fd, const std::vector<Extent>& extents, uint32_t block_size);
+  bool Init(FileDescriptorPtr fd,
+            const std::vector<Extent>& extents,
+            uint32_t block_size);
   bool Write(const void* bytes, size_t count);
   bool EndImpl();