diff --git a/src/slotmap.h b/src/slotmap.h
index 27d7e1b..af08a81 100644
--- a/src/slotmap.h
+++ b/src/slotmap.h
@@ -74,7 +74,7 @@
 struct slot_mapping *slotmap_by_bank(struct slotmaps *maps, const struct bank_slot *bank);
 
 /* thread-safe creating of a new bank<->client map */
-int slotmap_add(struct slotmaps *maps, const struct bank_slot *bank, const struct client_slot *client);
+struct slot_mapping *slotmap_add(struct slotmaps *maps, const struct bank_slot *bank, const struct client_slot *client);
 
 /* thread-safe removal of a bank<->client map */
 void slotmap_del(struct slotmaps *maps, struct slot_mapping *map);