diff --git a/src/mnesia/efka_client_store.erl b/src/mnesia/efka_client_store.erl
index 508b331..8cd0657 100644
--- a/src/mnesia/efka_client_store.erl
+++ b/src/mnesia/efka_client_store.erl
@@ -37,7 +37,7 @@ auth(UUID, Token) when is_binary(UUID), UUID =/= <<>>, is_binary(Token) ->
     end.
 
 -spec register(UUID :: binary(), Token :: binary()) -> ok | {error, term()}.
-register(UUID, Token) when is_binary(UUID), UUID =/= <<>>, is_binary(Token) ->
+register(UUID, Token) when is_binary(UUID), UUID =/= <<>>, is_binary(Token), byte_size(Token) >= 32 ->
     case mnesia:transaction(fun() ->
         case mnesia:read(efka_client, UUID, write) of
             [] ->