diff --git a/lib/environment.ml b/lib/environment.ml
index 2d64561..b4fb914 100644
--- a/lib/environment.ml
+++ b/lib/environment.ml
@@ -1,36 +1,38 @@
 open Value
 
-type env_table = (string, lox_value) Hashtbl.t
-type environment = { globals : env_table; locals : env_table list }
-
 module Hashtbl = struct
   include Stdlib.Hashtbl
 
   let contains tbl key = find_opt tbl key |> Option.is_some
 end
 
+type env_table = (string, lox_value) Hashtbl.t
+type environment = { globals : env_table ref; locals : env_table list }
+
 module Env = struct
   type t = environment
 
-  let make () : t = { globals = Hashtbl.create 0; locals = [] }
+  let make () : t = { globals = ref (Hashtbl.create 0); locals = [] }
 
   let enter (env : t) : t =
     let tbl = Hashtbl.create 0 in
     { env with locals = tbl :: env.locals }
 
-  let exit (env : t) : t =
-    assert (not (List.is_empty env.locals));
-    { env with locals = List.tl env.locals }
+  let push_frame (env : t) : t = { env with locals = [] } |> enter
+
+  (* let exit (env : t) : t =
+     assert (not (List.is_empty env.locals));
+     { env with locals = List.tl env.locals } *)
 
   let define_global (env : t) (name : string) (value : lox_value) =
-    Hashtbl.replace env.globals name value
+    Hashtbl.replace !(env.globals) name value
 
-  let get_global (env : t) (name : string) : lox_value option = Hashtbl.find_opt env.globals name
+  let get_global (env : t) (name : string) : lox_value option = Hashtbl.find_opt !(env.globals) name
 
   (* Check if `name` is defined in either locals or globals *)
   let is_defined (env : t) (name : string) : bool =
     let _is_defined tbl = Hashtbl.contains tbl name in
-    List.fold_left (fun acc tbl -> acc || _is_defined tbl) false (env.globals :: env.locals)
+    List.fold_left (fun acc tbl -> acc || _is_defined tbl) false (!(env.globals) :: env.locals)
 
   let define (env : t) (name : string) (value : lox_value) : bool =
     if List.is_empty env.locals then (
@@ -53,7 +55,7 @@ module Env = struct
             true)
           else _update tail
     in
-    if _update env.locals then () else Hashtbl.replace env.globals name value
+    if _update env.locals then () else Hashtbl.replace !(env.globals) name value
 
   let get (env : t) (name : string) : lox_value option =
     let rec _get tbls =
@@ -63,5 +65,5 @@ module Env = struct
           match Hashtbl.find_opt tbl name with Some x -> Some x | None -> _get tail)
     in
     let val_opt = _get env.locals in
-    match val_opt with Some x -> Some x | None -> Hashtbl.find_opt env.globals name
+    match val_opt with Some x -> Some x | None -> Hashtbl.find_opt !(env.globals) name
 end