diff --git a/src/ra_machine.erl b/src/ra_machine.erl
index f8fa5cdb..814e3030 100644
--- a/src/ra_machine.erl
+++ b/src/ra_machine.erl
@@ -251,7 +251,7 @@
 
 -callback snapshot_module() -> module().
 
--callback version() -> pos_integer().
+-callback version() -> version().
 
 -callback which_module(version()) -> module().