diff --git a/sstables/writer.hh b/sstables/writer.hh
index f7bc0ea877..0e00526f07 100644
--- a/sstables/writer.hh
+++ b/sstables/writer.hh
@@ -34,6 +34,10 @@
 
 namespace sstables {
 
+class index_sampling_state;
+class compression;
+class metadata_collector;
+
 class file_writer {
     output_stream<char> _out;
     writer_offset_tracker _offset;