diff --git a/compiler/global/clocks.ml b/compiler/global/clocks.ml
index 2b65c1d..5e1a4f3 100644
--- a/compiler/global/clocks.ml
+++ b/compiler/global/clocks.ml
@@ -78,6 +78,8 @@ let rec unify_ck ck1 ck2 =
 let rec unify t1 t2 =
   if t1 == t2 then () else
   match (t1, t2) with
+    | (Ck Cbase, Cprod [])
+    | (Cprod [], Ck Cbase) -> ()
     | (Ck ck1, Ck ck2) -> unify_ck ck1 ck2
     | (Cprod t1_list, Cprod t2_list) -> unify_list t1_list t2_list
     | _ -> raise Unify
diff --git a/compiler/heptagon/transformations/automata.ml b/compiler/heptagon/transformations/automata.ml
index 67c0502..c80d857 100644
--- a/compiler/heptagon/transformations/automata.ml
+++ b/compiler/heptagon/transformations/automata.ml
@@ -8,7 +8,7 @@
 (**************************************************************************)
 (* removing automata statements *)
 
-(* TODO deal correctly with [stateful] *)
+(* TODO deal correctly with [stateful] and [unsafe] *)
 
 open Misc
 open Types