diff --git a/src/ra_log.erl b/src/ra_log.erl
index cc20a23a..001ef9f9 100644
--- a/src/ra_log.erl
+++ b/src/ra_log.erl
@@ -136,7 +136,8 @@
       num_segments := non_neg_integer(),
       open_segments => non_neg_integer(),
       snapshot_index => undefined | ra_index(),
-      cache_size => non_neg_integer()}.
+      cache_size => non_neg_integer(),
+      atom() => term()}.
 
 -export_type([state/0,
               ra_log_init_args/0,