diff --git a/flap/src/hopix/hopixTypechecker.ml b/flap/src/hopix/hopixTypechecker.ml
index 0976d74..b55c267 100644
--- a/flap/src/hopix/hopixTypechecker.ml
+++ b/flap/src/hopix/hopixTypechecker.ml
@@ -444,11 +444,30 @@ and synth_read
   let refty = synth_expression tenv ref in
   HopixTypes.destruct_reference_type ref.position refty
 
+and synth_branch
+  :  HopixTypes.typing_environment -> HopixTypes.aty -> branch Position.located
+  -> HopixTypes.aty option -> HopixTypes.aty option
+  =
+  fun tenv casety branch branchty ->
+  let (Branch (p, e)) = branch.value in
+  let given_case, tenv' = synth_pattern tenv p in
+  check_equal_types p.position ~expected:casety ~given:given_case;
+  let given_branch = synth_expression tenv' e in
+  (match branchty with
+   | None -> ()
+   | Some ty' -> check_equal_types e.position ~expected:ty' ~given:given_branch);
+  Some given_branch
+
 and synth_case
   :  HopixTypes.typing_environment -> expression Position.located
   -> branch Position.located list -> HopixTypes.aty
   =
-  fun tenv expr branches -> failwith "Students! This is your job! (synth_case)"
+  fun tenv expr branches ->
+  let casety = synth_expression tenv expr in
+  (* Test les branches *)
+  match List.fold_right (synth_branch tenv casety) branches None with
+  | Some branchesty -> branchesty
+  | None -> HopixTypes.type_error expr.position "No types found."
 
 and synth_ifthenelse
   :  HopixTypes.typing_environment -> expression Position.located