diff --git a/ligo.opam b/ligo.opam
index d561c74d1..3a8d34feb 100644
--- a/ligo.opam
+++ b/ligo.opam
@@ -10,7 +10,9 @@ license: "MIT"
 # If you change the dependencies, run `opam lock` in the root
 depends: [
   # Jane Street Core
-  "core"
+  "core" { >= "v0.14.0" & < "v0.16.0" }
+  "core_kernel" { >= "v0.14.0" & "v0.16.0" }
+  "core_unix" { >= "v0.14.0" & "v0.16.0" }
   # Tooling
   "odoc" { build }
   "ocamlfind" { build }
diff --git a/ligo.opam.locked b/ligo.opam.locked
index b4501cc76..c8ed8a41f 100644
--- a/ligo.opam.locked
+++ b/ligo.opam.locked
@@ -50,8 +50,9 @@ depends: [
   "conf-rust" {= "0.1"}
   "conf-which" {= "1"}
   "coq" {= "8.13.2"}
-  "core" {= "v0.14.1"}
-  "core_kernel" {= "v0.14.2"}
+  "core" {= "v0.15.0"}
+  "core_kernel" {= "v0.15.0"}
+  "core_unix" {= "v0.15.0"}
   "cppo" {= "1.6.8"}
   "csexp" {= "1.5.1"}
   "cstruct" {= "6.0.1"}
diff --git a/src/bin/cli.ml b/src/bin/cli.ml
index a6fc13e0d..ef5177868 100644
--- a/src/bin/cli.ml
+++ b/src/bin/cli.ml
@@ -12,7 +12,7 @@ let entry_point =
 let source_file =
     let name = "SOURCE_FILE" in
     let _doc = "the path to the smart contract file." in
-    Command.Param.(anon (name %: Filename.arg_type))
+    Command.Param.(anon (name %: Filename_unix.arg_type))
 
 let package_name =
   let name = "PACKAGE_NAME" in
@@ -662,7 +662,7 @@ let main = Command.group ~preserve_subcommand_order:() ~summary:"the LigoLANG co
   ]
 
 let run ?argv () =
-  Command.run ~version:Version.version ?argv main;
+  Command_unix.run ~version:Version.version ?argv main;
   (* Effect to error code *)
   match !return with
     Done -> 0;
@@ -677,4 +677,3 @@ let run ?argv () =
     match exn with
     | Failure msg -> message msg
     | exn -> message (Exn.to_string exn)
-  
diff --git a/src/bin/cli_helpers.ml b/src/bin/cli_helpers.ml
index b64a17d53..8c4c43dde 100644
--- a/src/bin/cli_helpers.ml
+++ b/src/bin/cli_helpers.ml
@@ -66,7 +66,7 @@ let run_command (cmd : command) =
     (fun p -> Lwt.map  
       (fun status -> 
         match status with
-          Caml.Unix.WEXITED 0 -> Ok ()
+          Caml_unix.WEXITED 0 -> Ok ()
         | _ -> Error ("unknown error"))
         p#status) in
   Lwt_main.run status
\ No newline at end of file
diff --git a/src/bin/dune b/src/bin/dune
index 295c056f3..08d980439 100644
--- a/src/bin/dune
+++ b/src/bin/dune
@@ -11,7 +11,9 @@
   repl
   install
   cli_helpers
-  ligo_api)
+  ligo_api
+  core_unix.command_unix
+  core_unix.filename_unix)
  (modules cli version))
 
 (library
diff --git a/src/main/interpreter/dune b/src/main/interpreter/dune
index c55e24a88..f9762a297 100644
--- a/src/main/interpreter/dune
+++ b/src/main/interpreter/dune
@@ -4,4 +4,4 @@
  (instrumentation
   (backend bisect_ppx))
  (libraries tezos-011-PtHangz2-test-helpers ast_aggregated ligo_interpreter
-   main_errors ligo_compile build fuzz ligo_run self_ast_typed))
+   main_errors ligo_compile build fuzz ligo_run self_ast_typed core_unix.sys_unix))
diff --git a/src/main/interpreter/interpreter.ml b/src/main/interpreter/interpreter.ml
index b0379029c..530e08c3a 100644
--- a/src/main/interpreter/interpreter.ml
+++ b/src/main/interpreter/interpreter.ml
@@ -2,6 +2,7 @@ open Simple_utils.Trace
 open Simple_utils
 open Ligo_interpreter.Types
 open Ligo_interpreter.Combinators
+module Sys = Sys_unix
 
 module AST = Ast_aggregated
 
diff --git a/vendors/ligo-utils/simple-utils/dune b/vendors/ligo-utils/simple-utils/dune
index ca9f2bf5c..62c39087b 100644
--- a/vendors/ligo-utils/simple-utils/dune
+++ b/vendors/ligo-utils/simple-utils/dune
@@ -6,6 +6,7 @@
   (libraries
     ;; Third party
    core
+   core_kernel.caml_unix
    yojson
    result
    unix
diff --git a/vendors/ligo-utils/simple-utils/snippet.ml b/vendors/ligo-utils/simple-utils/snippet.ml
index 658f115f2..f23000590 100644
--- a/vendors/ligo-utils/simple-utils/snippet.ml
+++ b/vendors/ligo-utils/simple-utils/snippet.ml
@@ -1,7 +1,7 @@
 (* used to show code snippets in error messages *)
 
 let print_code ppf (l:Region.t) (input_line: unit -> string) =
-  let dumb =String.equal (Caml.Unix.getenv "TERM") "dumb" in
+  let dumb =String.equal (Caml_unix.getenv "TERM") "dumb" in
   let start = l#start#line in
   let start_column = l#start#offset `Byte in
   let stop = l#stop#line in