diff --git a/flap/src/hopix/hopixTypechecker.ml b/flap/src/hopix/hopixTypechecker.ml
index f4caabb..d65a001 100644
--- a/flap/src/hopix/hopixTypechecker.ml
+++ b/flap/src/hopix/hopixTypechecker.ml
@@ -49,10 +49,12 @@ let rec check_pattern_linearity
 
 and linearity_variable v vars =
   if List.mem v.value vars
-  then
-    HopixTypes.type_error
-      v.position
-      "Il y a déjà une occurence de la variable dans le pattern"
+  then (
+    match v.value with
+    | Id i ->
+      HopixTypes.type_error
+        v.position
+        (Printf.sprintf "The variable %s has already appeared in this pattern." i))
   else v.value :: vars
 
 and linearity_pattern_list plist vars =