diff --git a/simplifier.ml b/simplifier.ml
index 2ca9282..3822d60 100644
--- a/simplifier.ml
+++ b/simplifier.ml
@@ -1,15 +1,21 @@
 open Ast
+open Baselib
 
 let collect_constant_strings code =
   let counter = ref 0 in
+  let env = ref Env.empty in
   let ccs_value = function
     | V1.Void -> V2.Void, []
     | V1.Bool b -> V2.Bool b, []
     | V1.Int n -> V2.Int n, []
     | V1.Str s ->
-      incr counter;
-      let lbl = "str" ^ string_of_int !counter in
-      V2.Data lbl, [ lbl, Mips.Asciiz s ]
+      (match Env.find_opt s !env with
+      | Some lbl -> V2.Data lbl, [ lbl, Mips.Asciiz s ]
+      | None ->
+        incr counter;
+        let lbl = "str" ^ string_of_int !counter in
+        env := Env.add s lbl !env;
+        V2.Data lbl, [ lbl, Mips.Asciiz s ])
   in
   let rec ccs_expr = function
     | IR1.Val v ->
@@ -17,8 +23,8 @@ let collect_constant_strings code =
       IR2.Val v2, cs
     | IR1.Var v -> IR2.Var v, []
     | IR1.Call (fn, args) ->
-      let a2 = List.map ccs_expr args in
-      IR2.Call (fn, List.map fst a2), List.flatten (List.map snd a2)
+      let args2 = List.map ccs_expr args in
+      IR2.Call (fn, List.map fst args2), List.flatten (List.map snd args2)
   in
   let ccs_instr = function
     | IR1.Decl v -> IR2.Decl v, []
@@ -43,7 +49,11 @@ let collect_constant_strings code =
     IR2.Func (name, args, body2), cs
   in
   let code2 = List.map ccs_def code in
-  List.map fst code2, List.flatten (List.map snd code2)
+  ( List.map fst code2
+  , List.fold_left
+      (fun list el -> if List.mem el list then list else el :: list)
+      []
+      (List.flatten (List.map snd code2)) )
 ;;
 
 let simplify ir = collect_constant_strings ir