diff --git a/flap/src/hopix/hopixTypechecker.ml b/flap/src/hopix/hopixTypechecker.ml
index c17f29e..57cd879 100644
--- a/flap/src/hopix/hopixTypechecker.ml
+++ b/flap/src/hopix/hopixTypechecker.ml
@@ -145,9 +145,11 @@ and synth_tannot
   :  HopixTypes.typing_environment -> expression Position.located -> ty Position.located
   -> HopixTypes.aty
   =
-  fun tenv expr t ->
-  (* TODO : ici on ne peut pas synthesisé. cf Cours*)
-  failwith "Students! This is your job! (synth_tannot)"
+  fun tenv expr ty ->
+  (* Pas sûr de ça *)
+  let ty' = synth_expression tenv expr in
+  check_equal_types expr.position ~expected:(HopixTypes.internalize_ty tenv ty) ~given:ty';
+  ty'
 
 and synth_field
   :  HopixTypes.typing_environment -> expression Position.located