diff --git a/src/aeb_fate_maps.erl b/src/aeb_fate_maps.erl
index dcec997..1d7c189 100644
--- a/src/aeb_fate_maps.erl
+++ b/src/aeb_fate_maps.erl
@@ -20,7 +20,7 @@
         , refcount_union/2
         , no_used_ids/0 ]).
 
--export_type([used_ids/0, maps/0]).
+-export_type([used_ids/0, maps/0, refcount/0]).
 
 %% Size in bytes of serialization of a map for which we turn it into a store
 %% map. It's not worth turning small maps into store maps.