diff --git a/runtime/runtime.c b/runtime/runtime.c
index 6e0bfe294..133b72c7b 100644
--- a/runtime/runtime.c
+++ b/runtime/runtime.c
@@ -124,10 +124,24 @@ void Lprintf (char *s, ...) {
   va_list args;
 
   va_start (args, s);
-  vprintf (s, args);
+  vprintf (s, args); // vprintf (char *, va_list) <-> printf (char *, ...) 
   va_end (args);
 }
 
+void* Lstrcat (void *a, void *b) {
+  data *da = TO_DATA(a);
+  data *db = TO_DATA(b);
+  
+  data *d  = (data *) malloc (sizeof(int) + LEN(da->tag) + LEN(db->tag) + 1);
+
+  d->tag = LEN(da->tag) + LEN(db->tag);
+
+  strcpy (d->contents, da->contents);
+  strcat (d->contents, db->contents);
+
+  return d->contents;
+}
+
 void Lfprintf (FILE *f, char *s, ...) {
   va_list args;
 
diff --git a/src/Language.ml b/src/Language.ml
index b3bf9c7d6..0318ba7be 100644
--- a/src/Language.ml
+++ b/src/Language.ml
@@ -231,13 +231,19 @@ module Expr =
 	  !(Ostap.Util.expr 
              (fun x -> x)
 	     (Array.map (fun (a, s) -> a, 
-                           List.map (fun s -> ostap(- $(s)), (fun x y -> Binop (s, x, y))) s
+                                       List.map (fun s -> ostap(- $(s)),
+                                                          (fun x y ->
+                                                            match s with
+                                                              "++" -> Call ("strcat", [x; y])
+                                                             | _ -> Binop (s, x, y)
+                                                          )
+                                         ) s
                         ) 
               [|                
 		`Lefta, ["!!"];
 		`Lefta, ["&&"];
 		`Nona , ["=="; "!="; "<="; "<"; ">="; ">"];
-		`Lefta, ["+" ; "-"];
+		`Lefta, ["++"; "+" ; "-"];
 		`Lefta, ["*" ; "/"; "%"];
               |] 
 	     )