diff --git a/pieuvre.ml b/pieuvre.ml
index f26cea5..ac17afe 100644
--- a/pieuvre.ml
+++ b/pieuvre.ml
@@ -23,11 +23,11 @@ let rec string_of_lam (l: lam) : string = match l with
 
 let split, tsplit =
     let splitter regex x =
-    if string_match regex x 0
+    if (string_match regex x 0)
         then
             let xStr = matched_group 1 x in
             let xInt = matched_group 2 x in
-            (xStr, int_of_string xInt)
+            (xStr, if xInt="" then 0 else (int_of_string xInt))
 
     else raise (IllegalVarNameException(x))
     in (splitter varRegex, splitter tvarRegex);;
@@ -81,7 +81,7 @@ let rec alpha (l1: lam) (l2: lam) : bool =
             (t1 = t2) &&
             (* On trouve un nom libre dans les deux sous-termes *)
             let v' = findFreeName (LApp(l1', l2')) v1 in
-            alpha (replace l1 v1 (LVar(v'))) (replace l2 v2 (LVar(v')))
+            alpha (replace l1' v1 (LVar(v'))) (replace l2' v2 (LVar(v')))
         | (LApp(lf1,lx1),LApp(lf2,lx2)) -> (alpha lf1 lf2) && (alpha lx1 lx2)
         | (LVar(x1),LVar(x2)) -> x1 = x2
         | (LExf(l1', t1),LExf(l2', t2)) -> t1=t2 && (alpha l1' l2')
diff --git a/structs.ml b/structs.ml
index d789846..ede5557 100644
--- a/structs.ml
+++ b/structs.ml
@@ -1,13 +1,13 @@
 (* Variables des λ-termes *)
 type var_lambda = string;;
 type var = var_lambda;; (* TODEL *)
-let varRegex = Str.regexp "^([a-z]+)([0-9]*)$";;
+let varRegex = Str.regexp "^\\([a-z]+\\)\\([0-9]*\\)$";;
 
 (* Variable des types simples *)
 type var_type = string;;
 type tvar = var_type;; (* TODEL *)
 
-let tvarRegex = Str.regexp "^([A-Z]+)([0-9]*)$";;
+let tvarRegex = Str.regexp "^([A-Z]+)([0-9]*)?$";;
 
 (* Type complexe *)
 type ty =