diff --git a/bin/commandLockdown.ml b/bin/commandLockdown.ml
index 48e452d..1473e25 100644
--- a/bin/commandLockdown.ml
+++ b/bin/commandLockdown.ml
@@ -30,10 +30,11 @@ let lockdown_save_command =
           "_build"
         |> Option.some
       in
-      let _env = Setup.read_environment () in
+      let env = Setup.read_environment () in
       (fun () ->
          Satyrographos_command.Lockdown.save_lockdown
            ~verbose
+           ~env
            ~buildscript_path;
          reprint_err_warn ())
     ]
@@ -50,10 +51,11 @@ let lockdown_restore_command =
       in
       Compatibility.optin ();
       let buildscript_path = Option.value ~default:(default_script_path ()) script in
-      let _env = Setup.read_environment () in
+      let env = Setup.read_environment () in
       (fun () ->
          Satyrographos_command.Lockdown.restore_lockdown
            ~verbose
+           ~env
            ~buildscript_path;
          reprint_err_warn ())
     ]
diff --git a/bin/setup.ml b/bin/setup.ml
index 245ffc0..ef65612 100644
--- a/bin/setup.ml
+++ b/bin/setup.ml
@@ -13,9 +13,8 @@ let default_target_dir =
   |> Option.value ~default:(Filename.concat home_dir ".satysfi")
   |> (fun dir -> Filename.concat dir "dist")
 
-let read_environment () =
+let read_environment ?opam_switch () =
   let outf = Format.std_formatter in
-  let env = EnvironmentStatus.read_opam_environment () in
-  Format.(fprintf std_formatter !"env: %{sexp: Environment.t}\n" env);
+  let env = EnvironmentStatus.read_opam_environment ?opam_switch () in
   SatysfiDirs.read_satysfi_env ~outf env
 
diff --git a/bin/setup.mli b/bin/setup.mli
index 5b531fb..da3b53e 100644
--- a/bin/setup.mli
+++ b/bin/setup.mli
@@ -3,4 +3,4 @@ val default_target_dir : string
 
 (** Read current runtime-dependent information.
     This command SHOULD NOT affect the environment. *)
-val read_environment : unit -> Satyrographos.Environment.t
+val read_environment : ?opam_switch:OpamTypes.switch -> unit -> Satyrographos.Environment.t
diff --git a/satyrographos.opam b/satyrographos.opam
index f1e447a..25c73f7 100644
--- a/satyrographos.opam
+++ b/satyrographos.opam
@@ -29,13 +29,8 @@ depends: [
   "ppx_deriving"
   "ppx_deriving_yojson"
   "ocamlgraph"
-  ( "opam-format" {>= "2.0.4" & < "2.2"}
-    & "opam-state" {>= "2.0.4" & < "2.2"}
-    & "ocaml" {< "4.12.0"}
-  | "opam-format" {>= "2.1.0" & < "2.2"}
-    & "opam-state" {>= "2.1.0" & < "2.2"}
-    & "ocaml" {>= "4.12.0"}
-  )
+  "opam-format" {>= "2.0" & < "2.2"}
+  "opam-state" {>= "2.0" & < "2.2"}
   "re" { >= "1.9.0" }
   "stringext" {with-test}
   "uri" {>= "3.0.0"}
diff --git a/src/command/lockdown.ml b/src/command/lockdown.ml
index 6727489..ca7ce28 100644
--- a/src/command/lockdown.ml
+++ b/src/command/lockdown.ml
@@ -10,11 +10,12 @@ let load_lockdown_file ~buildscript_path =
   then Some (Satyrographos_lockdown.LockdownFile.load_file_exn path)
   else None
 
-let save_lockdown ~verbose ~buildscript_path =
+let save_lockdown ~verbose ~env ~buildscript_path =
   let buildscript = Satyrographos.BuildScript.load buildscript_path in
   let lockdown =
     Satyrographos_lockdown.Lockdown.generate_lockdown
       ~verbose
+      ~env
       ~buildscript
   in
   Satyrographos_lockdown.LockdownFile.save_file_exn
diff --git a/src/environmentStatus.ml b/src/environmentStatus.ml
index a8d29d3..ba79bbb 100644
--- a/src/environmentStatus.ml
+++ b/src/environmentStatus.ml
@@ -1,21 +1,10 @@
+(*
 open Core
 
-(*
 let satysfi_opam_registry () =
   OpamWrapper.get_satysfi_opam_registry None
   |> Option.map ~f:OpamFilename.Dir.to_string
 *)
 
 let read_opam_environment ?opam_switch () =
-  let satysfi_opam_registry () =
-    OpamWrapper.get_satysfi_opam_registry opam_switch
-    |> Option.map ~f:OpamFilename.Dir.to_string
-  in
-
-  let reg = satysfi_opam_registry () in
-  Format.(printf !"reg: %{sexp: string option}\n" reg);
-
-  let opam_reg =
-    OpamSatysfiRegistry.read (reg |> Option.value_exn ~message:"Failed to read OPAM repo")
-  in
-  Environment.{ empty with opam_reg; opam_switch; }
+  OpamWrapper.read_opam_environment ?opam_switch Environment.empty
diff --git a/src/lockdown/lockdown.ml b/src/lockdown/lockdown.ml
index 9b34b87..7f1147c 100644
--- a/src/lockdown/lockdown.ml
+++ b/src/lockdown/lockdown.ml
@@ -1,6 +1,6 @@
 open Core
 
-let generate_lockdown ~verbose ~buildscript =
+let generate_lockdown ~verbose ~env ~buildscript =
   let open Satyrographos in
   let dependent_opam_packages =
     BuildScript.get_opam_dependencies buildscript
@@ -24,7 +24,7 @@ let generate_lockdown ~verbose ~buildscript =
   LockdownFile.make
     ~dependencies:
       (LockdownFile.Opam
-         (OpamDependencies.get_opam_dependencies ~verbose dependent_opam_packages))
+         (OpamDependencies.get_opam_dependencies ~verbose ~env dependent_opam_packages))
     ~autogen
 
 let restore_lockdown ~verbose (lockdown : LockdownFile.t) =
diff --git a/src/lockdown/opamDependencies.ml b/src/lockdown/opamDependencies.ml
index b589dea..ea70eba 100644
--- a/src/lockdown/opamDependencies.ml
+++ b/src/lockdown/opamDependencies.ml
@@ -8,11 +8,11 @@ let get_opam_repositories ~gt ~rt () =
   OpamGlobalState.repos_list gt
   |> List.map ~f:(OpamRepositoryState.get_repo rt)
 
-let get_opam_dependencies ~verbose packages =
+let get_opam_dependencies ~verbose ~env packages =
   OpamGlobalState.with_ `Lock_none @@ fun gt ->
   OpamRepositoryState.with_ `Lock_none gt @@ fun rt ->
   let package_and_repos =
-    OpamWrapper.opam_installed_transitive_dependencies_com ~verbose packages
+    OpamWrapper.opam_installed_transitive_dependencies_com ~verbose ~env packages
     |> P.eval
   in
   let packages =
@@ -79,14 +79,14 @@ let get_opam_dependencies ~verbose packages =
   end;
   { packages; repos; }
 
-let restore_opam_dependencies_com ~verbose (dependencies : opam_dependencies) =
+let restore_opam_dependencies_com ~verbose ~env (dependencies : opam_dependencies) =
   let packages =
     dependencies.packages
     |> List.map ~f:(fun {name; version;} ->
         name, version)
   in
-  let install_com =
-    OpamWrapper.opam_install_com ~verbose packages
+  let install_com env =
+    OpamWrapper.opam_install_com ~env ~verbose packages
   in
   let repos =
     dependencies.repos
@@ -94,10 +94,10 @@ let restore_opam_dependencies_com ~verbose (dependencies : opam_dependencies) =
   in
   let open P.Infix in
   OpamWrapper.opam_clean_up_local_switch_com ()
-  >> OpamWrapper.opam_set_up_local_switch_com ~repos ~version:None ()
-  >> install_com
+  >> OpamWrapper.opam_set_up_local_switch_com ~env ~repos ~version:None ()
+  >>= install_com
 
 
-let restore_opam_dependencies ~verbose (dependencies : opam_dependencies) =
-  restore_opam_dependencies_com ~verbose dependencies
+let restore_opam_dependencies ~verbose ~env (dependencies : opam_dependencies) =
+  restore_opam_dependencies_com ~verbose ~env dependencies
   |> P.eval
diff --git a/src/opamWrapper.ml b/src/opamWrapper.ml
index 72b7901..8319339 100644
--- a/src/opamWrapper.ml
+++ b/src/opamWrapper.ml
@@ -22,11 +22,8 @@ let opam_package_name_satysfi = OpamPackage.Name.(of_string "satysfi")
 let get_satysfi_opam_registry switch =
   let get_reg_from_root switch =
     let root = OpamStateConfig.(!r.root_dir) in
-    Format.(OpamFilename.Dir.to_string root |> printf !"root: %s\n");
     let switch_config_file = OpamPath.Switch.switch_config root switch in
-    Format.(OpamFile.to_string switch_config_file |> printf !"switch_config_file: %s\n");
     let switch_config = OpamFile.Switch_config.read switch_config_file in
-    Format.(OpamFile.Switch_config.write_to_string switch_config |> printf !"switch_config: %s\n");
     OpamPath.Switch.share root switch switch_config opam_package_name_satysfi
   in
   OpamGlobalState.with_ `Lock_none @@ fun gt ->
@@ -73,7 +70,21 @@ let default_repo_list =
     "https://opam.ocaml.org/";
   ]
 
+let opam_switch_arg opam_switch =
+  "--switch=" ^ OpamSwitch.to_string opam_switch
 
+let read_opam_environment ?opam_switch env =
+  let satysfi_opam_registry () =
+    get_satysfi_opam_registry opam_switch
+    |> Option.map ~f:OpamFilename.Dir.to_string
+  in
+
+  let reg = satysfi_opam_registry () in
+
+  let opam_reg =
+    OpamSatysfiRegistry.read (reg |> Option.value_exn ~message:"Failed to read OPAM repo")
+  in
+  Environment.{ env with opam_reg; opam_switch; }
 
 let opam_clean_up_local_switch_com ?(path="./") () =
   let open P.Infix in
@@ -98,7 +109,9 @@ let opam_clean_up_local_switch_com ?(path="./") () =
   else P.return ()
 
 
-let opam_set_up_local_switch_com ?(repos=default_repo_list) ?(path="./") ~version () =
+let opam_set_up_local_switch_com ~(env: Environment.t) ?(repos=default_repo_list) ?(path="./") ~version () =
+  let opam_switch = OpamSwitch.of_dirname @@ OpamFilename.Dir.of_string path in
+  let open P.Infix in
   let args = [
     "switch";
     "create";
@@ -116,6 +129,9 @@ let opam_set_up_local_switch_com ?(repos=default_repo_list) ?(path="./") ~versio
   ]
   in
   P.run "opam" args
+  >>| (fun () ->
+      read_opam_environment ~opam_switch env
+    )
 
 
 type opam_dependency_wrapper = {
@@ -124,10 +140,10 @@ type opam_dependency_wrapper = {
   version: string;
 }
 
-let opam_installed_transitive_dependencies_com ~verbose:_ packages =
+let opam_installed_transitive_dependencies_com ~verbose:_ ~(env: Environment.t) packages =
   let open P.Infix in
   let cmd =
-    P.run "opam" [
+    [
       "list";
       "-i";
       "--color=never";
@@ -136,6 +152,8 @@ let opam_installed_transitive_dependencies_com ~verbose:_ packages =
       "--separator=,";
       "--recursive";
       "--required-by"; String.concat ~sep:"," packages]
+    @ Option.value_map env.opam_switch ~default:[] ~f:(fun switch -> [opam_switch_arg switch])
+    |> P.run "opam"
     |> P.capture_unit [P.Std_io.Stdout]
     >>| String.split_lines
     >>| List.filter ~f:(fun l -> String.is_prefix ~prefix:"#" l |> not)
@@ -161,7 +179,7 @@ let get_opam_repositories ~gt ~rt () =
   OpamGlobalState.repos_list gt
   |> List.map ~f:(OpamRepositoryState.get_repo rt)
 
-let opam_install_com ~verbose packages =
+let opam_install_com ~(env: Environment.t) ~verbose packages =
   let packages =
     packages
     |> List.map ~f:(fun (name, version) ->
@@ -169,7 +187,9 @@ let opam_install_com ~verbose packages =
   in
   [
     ["install"; "--yes";];
-    ["--switch=.";];
+    Option.value_map env.opam_switch ~default:[] ~f:(fun opam_switch ->
+        [opam_switch_arg opam_switch]
+      );
     if verbose
     then ["--verbose";]
     else [];
@@ -179,14 +199,19 @@ let opam_install_com ~verbose packages =
   |> P.run "opam"
   |> with_dune_cache
 
-let opam_install ~verbose packages =
-  opam_install_com ~verbose packages
+let opam_install ~(env: Environment.t) ~verbose packages =
+  opam_install_com ~env ~verbose packages
   |> P.eval
 
-let opam_exec_run com args =
-  [
-    "exec";
-    "--switch=.";
-    "--";
-  ] @ [com] @ args
-  |> P.run "opam"
+
+let exec_run ~(env: Environment.t) com args =
+  match env.opam_switch with
+  | None ->
+    P.run com args
+  | Some opam_switch ->
+    [
+      "exec";
+      opam_switch_arg opam_switch;
+      "--";
+    ] @ [com] @ args
+    |> P.run "opam"
diff --git a/src/satysfi/satysfiDirs.ml b/src/satysfi/satysfiDirs.ml
index 58e33b5..c540982 100644
--- a/src/satysfi/satysfiDirs.ml
+++ b/src/satysfi/satysfiDirs.ml
@@ -32,7 +32,7 @@ let option_to_list = function
   | Some x -> [x]
   | None -> []
 
-let dist_library_dir ?satysfi_opam_reg ~outf:_ =
+let dist_library_dir ~satysfi_opam_reg ~outf:_ =
 
   let shares = ["/usr/local/share"; "/usr/share"] in
   let dist_dirs =
@@ -51,5 +51,5 @@ let dist_library_dir ?satysfi_opam_reg ~outf:_ =
 
 
 let read_satysfi_env ~outf (env: Satyrographos.Environment.t) =
-  let dist_library_dir = dist_library_dir ?satysfi_opam_reg:(Option.map env.opam_reg ~f:(fun reg -> reg.registry_dir)) ~outf in
+  let dist_library_dir = dist_library_dir ~satysfi_opam_reg:(Option.map env.opam_reg ~f:(fun reg -> reg.registry_dir)) ~outf in
   { env with dist_library_dir }
diff --git a/test/testcases/command_build__doc_with_autogen.ml b/test/testcases/command_build__doc_with_autogen.ml
index fde0cf5..eabede2 100644
--- a/test/testcases/command_build__doc_with_autogen.ml
+++ b/test/testcases/command_build__doc_with_autogen.ml
@@ -42,6 +42,11 @@ dependencies:
     version: 0.0.2.7
   - name: satysfi
     version: 0.0.5+dev2020.09.05
+  repos:
+  - name: default
+    url: https://opam.ocaml.org/
+  - name: satysfi-external
+    url: git+https://github.com/gfngfn/satysfi-external-repo.git
 autogen:
   '$today':
     datetime: 2020-11-06T00:46:35.000000+09:00
diff --git a/test/testcases/command_lockdown_restore__opam.ml b/test/testcases/command_lockdown_restore__opam.ml
index e1f01bb..90c9053 100644
--- a/test/testcases/command_lockdown_restore__opam.ml
+++ b/test/testcases/command_lockdown_restore__opam.ml
@@ -16,6 +16,11 @@ dependencies:
     version: 0.0.2.7
   - name: satysfi
     version: 0.0.5+dev2020.09.05
+  repos:
+  - name: default
+    url: https://opam.ocaml.org/
+  - name: satysfi-external
+    url: git+https://github.com/gfngfn/satysfi-external-repo.git
 autogen:
   '$today':
     time: 2020-11-06T00:46:35.000000+09:00
@@ -54,11 +59,12 @@ let env ~dest_dir:_ ~temp_dir : Satyrographos.Environment.t t =
 
 let () =
   let verbose = false in
-  let main _env ~dest_dir:_ ~temp_dir ~outf:_ =
+  let main env ~dest_dir:_ ~temp_dir ~outf:_ =
     let _name = Some "example-doc" in
     (* let dest_dir = FilePath.concat dest_dir "dest" in *)
     Satyrographos_command.Lockdown.restore_lockdown
       ~verbose
+      ~env
       ~buildscript_path:(FilePath.concat temp_dir "pkg/Satyristes")
   in
   let post_dump_dirs ~dest_dir:_ ~temp_dir:_ = [] in
diff --git a/test/testcases/command_lockdown_save__invalid_opam_response.ml b/test/testcases/command_lockdown_save__invalid_opam_response.ml
index 8e68700..426957e 100644
--- a/test/testcases/command_lockdown_save__invalid_opam_response.ml
+++ b/test/testcases/command_lockdown_save__invalid_opam_response.ml
@@ -9,7 +9,7 @@ let files =
   Command_lockdown_save__opam.files
 
 let opam_response = {
-  PrepareBin.list_result = {|***invalid,response,!!!|}
+  PrepareBin.list_result = {|***,invalid,response,!!!|}
 }
 
 let env ~dest_dir:_ ~temp_dir : Satyrographos.Environment.t t =
@@ -38,11 +38,12 @@ let env ~dest_dir:_ ~temp_dir : Satyrographos.Environment.t t =
 
 let () =
   let verbose = false in
-  let main _env ~dest_dir:_ ~temp_dir ~outf:_ =
+  let main env ~dest_dir:_ ~temp_dir ~outf:_ =
     let _name = Some "example-doc" in
     (* let dest_dir = FilePath.concat dest_dir "dest" in *)
     Satyrographos_command.Lockdown.save_lockdown
       ~verbose
+      ~env
       ~buildscript_path:(FilePath.concat temp_dir "pkg/Satyristes")
   in
   let post_dump_dirs ~dest_dir:_ ~temp_dir =
diff --git a/test/testcases/command_lockdown_save__opam.ml b/test/testcases/command_lockdown_save__opam.ml
index 62fb55a..1099371 100644
--- a/test/testcases/command_lockdown_save__opam.ml
+++ b/test/testcases/command_lockdown_save__opam.ml
@@ -65,10 +65,10 @@ let files =
 
 let opam_response = {
   PrepareBin.list_result = {|# Packages matching: (installed | available) & (name-match(satyrographos) | name-match(satysfi) | name-match(ocaml))
-# Name       ,# Version
-ocaml        ,4.09.0
-satyrographos,0.0.2.7
-satysfi      ,0.0.5+dev2020.09.05|}
+# Name       ,# Repository    ,# Version
+ocaml        ,default         ,4.09.0
+satyrographos,satysfi-external,0.0.2.7
+satysfi      ,satyrographos   ,0.0.5+dev2020.09.05|}
 }
 
 let env ~dest_dir:_ ~temp_dir : Satyrographos.Environment.t t =
@@ -97,11 +97,12 @@ let env ~dest_dir:_ ~temp_dir : Satyrographos.Environment.t t =
 
 let () =
   let verbose = false in
-  let main _env ~dest_dir:_ ~temp_dir ~outf:_ =
+  let main env ~dest_dir:_ ~temp_dir ~outf:_ =
     let _name = Some "example-doc" in
     (* let dest_dir = FilePath.concat dest_dir "dest" in *)
     Satyrographos_command.Lockdown.save_lockdown
       ~verbose
+      ~env
       ~buildscript_path:(FilePath.concat temp_dir "pkg/Satyristes")
   in
   let post_dump_dirs ~dest_dir:_ ~temp_dir =
diff --git a/test/testlib/testLib.ml b/test/testlib/testLib.ml
index d49c2d8..5889ebb 100644
--- a/test/testlib/testLib.ml
+++ b/test/testlib/testLib.ml
@@ -80,7 +80,10 @@ let dump_dir dir : unit t =
   )
   |> set_env "LC_ALL" "C"
 
-let stacktrace = false
+let stacktrace =
+  Sys.getenv_opt "SATYROGRAPHOS_TEST_STACKTRACE"
+  |> Option.map (String.equal "true")
+  |> Option.value ~default:false
 
 let filter_output f c =
   capture [Std_io.Stdout] c