diff --git a/src/passes/2-simplify/pascaligo.ml b/src/passes/2-simplify/pascaligo.ml
index 44dd0afda..1998f1c85 100644
--- a/src/passes/2-simplify/pascaligo.ml
+++ b/src/passes/2-simplify/pascaligo.ml
@@ -89,17 +89,6 @@ module Errors = struct
     ] in
     error ~data title message
 
-  let unsupported_string_catenation expr =
-    let title () = "string expressions" in
-    let message () =
-      Format.asprintf "string concatenation is not supported yet" in
-    let expr_loc = Raw.expr_to_region expr in
-    let data = [
-      ("expr_loc",
-       fun () -> Format.asprintf "%a" Location.pp_lift @@ expr_loc)
-    ] in
-    error ~data title message
-
   let unsupported_proc_calls call =
     let title () = "procedure calls" in
     let message () =
diff --git a/src/passes/2-simplify/pascaligo.mli b/src/passes/2-simplify/pascaligo.mli
index 0d22c29c6..ccc42e5e1 100644
--- a/src/passes/2-simplify/pascaligo.mli
+++ b/src/passes/2-simplify/pascaligo.mli
@@ -29,7 +29,6 @@ module Errors : sig
   *)
   val unsupported_arith_op : Raw.expr -> unit -> error
   (*
-  val unsupported_string_catenation : Raw.expr -> unit -> error
   val unsupported_set_expr : Raw.expr -> unit -> error
   *)
   val unsupported_proc_calls : 'a Raw.reg -> unit -> error
diff --git a/src/stages/ast_simplified/combinators.mli b/src/stages/ast_simplified/combinators.mli
index a5cc91887..764b7ca16 100644
--- a/src/stages/ast_simplified/combinators.mli
+++ b/src/stages/ast_simplified/combinators.mli
@@ -61,6 +61,7 @@ val e_record  : ?loc:Location.t -> ( expr * expr ) list -> expression
 val e_tuple : ?loc:Location.t -> expression list -> expression
 val e_some : ?loc:Location.t -> expression -> expression
 val e_none : ?loc:Location.t -> unit -> expression
+val e_string_cat : ?loc:Location.t -> expression -> expression -> expression
 val e_map_add : ?loc:Location.t -> expression -> expression ->  expression -> expression
 val e_map : ?loc:Location.t -> ( expression * expression ) list -> expression
 val e_set : ?loc:Location.t -> expression list -> expression