diff --git a/lib/lox.ml b/lib/lox.ml
index 14e776a..5d88c74 100644
--- a/lib/lox.ml
+++ b/lib/lox.ml
@@ -4,14 +4,20 @@ module Error = Error
 module Expr = Expr
 module Interpreter = Interpreter
 module Lexer = Lexer
+module Loxstd = Loxstd
 module Parser = Parser
 module Stmt = Stmt
 
 type lox_error = Error.lox_error
 
+let make_env_with_std () =
+  let env = Environment.Env.make () in
+  Loxstd.init_std env;
+  env
+
 let run ?(env : Environment.environment option) ?(debug = false) (source : string) :
     (unit, lox_error) result =
-  let env = Option.value env ~default:(Environment.Env.make ()) in
+  let env = Option.value env ~default:(make_env_with_std ()) in
   let* tokens = Error.of_lexer_error (Lexer.tokenize source) in
   let () =
     if debug then
@@ -50,12 +56,12 @@ let run ?(env : Environment.environment option) ?(debug = false) (source : strin
   interpret_stmts stmts |> Error.of_runtimer_error
 
 let runRepl ?(debug = false) () : unit =
-  let env = Environment.Env.make () in
+  let env = make_env_with_std () in
   try
     while true do
       print_string "> ";
       let line = read_line () in
       let result = run ~env ~debug line in
-      Result.iter_error Error.print_error result
+      Result.map_error Error.print_error result |> ignore
     done
   with End_of_file -> ()