diff --git a/doc/create.txt b/doc/create.txt
index 3c5ed6b..db4ff23 100644
--- a/doc/create.txt
+++ b/doc/create.txt
@@ -18,6 +18,9 @@ DESCRIPTION
 
        Github pull request (short form)
            #number (repo defaults to "ocaml/ocaml")
+
+       Directory
+           path/to/sources
 ARGUMENTS
        SOURCE (required)
            Where to fetch the compiler.
diff --git a/doc/dune b/doc/dune
index e94a183..2dc3b9b 100644
--- a/doc/dune
+++ b/doc/dune
@@ -17,3 +17,13 @@
  (alias runtest)
  (action
   (diff create.txt create.txt.gen)))
+
+(rule
+ (with-stdout-to
+  reinstall.txt.gen
+  (run opam-compiler reinstall --help=plain)))
+
+(rule
+ (alias runtest)
+ (action
+  (diff reinstall.txt reinstall.txt.gen)))
diff --git a/doc/opam-compiler.txt b/doc/opam-compiler.txt
index cd702b5..c14d6a1 100644
--- a/doc/opam-compiler.txt
+++ b/doc/opam-compiler.txt
@@ -8,6 +8,9 @@ COMMANDS
        create
            Create a switch from a compiler source
 
+       reinstall
+           Reinstall the compiler
+
 OPTIONS
        --help[=FMT] (default=auto)
            Show this help in format FMT. The value FMT must be one of `auto',
diff --git a/doc/reinstall.txt b/doc/reinstall.txt
new file mode 100644
index 0000000..cd7a33a
--- /dev/null
+++ b/doc/reinstall.txt
@@ -0,0 +1,38 @@
+NAME
+       opam-compiler-reinstall - Reinstall the compiler
+
+SYNOPSIS
+       opam-compiler reinstall [OPTION]... 
+
+       Reinstall the compiler will propagate the changes done to its source.
+
+       There are two ways to reinstall:
+
+       Full (default)
+           Reinstall the compiler and all the packages in the switch. This
+           can be slow but is always safe.
+
+       Quick (unsafe)
+           Only reinstall the compiler. This is fast, but will break the
+           switch if the way it compiles is modified for example.
+OPTIONS
+       --dry-run
+           Do not perform external commands. Print them and continue as if
+           they worked.
+
+       --full
+           Perform a full reinstallation (default).
+
+       --help[=FMT] (default=auto)
+           Show this help in format FMT. The value FMT must be one of `auto',
+           `pager', `groff' or `plain'. With `auto', the format is `pager` or
+           `plain' whenever the TERM env var is `dumb' or undefined.
+
+       --quick
+           Perform a quick reinstallation (unsafe)
+
+       --switch=SWITCH_NAME
+           Use this name for the switch. If omitted, a name is inferred from
+           the source. This name is used as is by opam, so passing "." will
+           create a local switch in the current directory.
+
diff --git a/lib/cli.ml b/lib/cli.ml
index 02b998e..c080801 100644
--- a/lib/cli.ml
+++ b/lib/cli.ml
@@ -8,10 +8,17 @@ type t =
       runner : Runner.t;
       github_client : Github_client.t;
     }
+  | Reinstall of {
+      mode : Op.reinstall_mode;
+      switch_name : Switch_name.t option;
+      runner : Runner.t;
+    }
 
 let eval = function
   | Create { source; switch_name; configure_command; runner; github_client } ->
       Op.create runner github_client source switch_name ~configure_command
+  | Reinstall { mode; switch_name; runner } ->
+      Op.reinstall runner mode ~name:switch_name
 
 let configure_command_explicit =
   let open Cmdliner.Arg in
@@ -66,14 +73,46 @@ let configure_command =
   in
   Cmdliner.Term.ret ret_term
 
+let dry_run =
+  let open Cmdliner.Arg in
+  let info =
+    info
+      ~doc:
+        "Do not perform external commands. Print them and continue as if they \
+         worked."
+      [ "dry-run" ]
+  in
+  value (flag info)
+
+let clients =
+  let open Let_syntax.Cmdliner in
+  let+ dry_run = dry_run in
+  let runner = if dry_run then Runner.dry_run else Runner.real in
+  let github_client =
+    if dry_run then Github_client.dry_run else Github_client.real
+  in
+  (runner, github_client)
+
+let switch_name =
+  let open Cmdliner.Arg in
+  let conv = conv (Switch_name.parse, Switch_name.pp) in
+  value
+    (opt (some conv) None
+       (info ~docv:"SWITCH_NAME"
+          ~doc:
+            "Use this name for the switch. If omitted, a name is inferred from \
+             the source. This name is used as is by opam, so passing \".\" \
+             will create a local switch in the current directory."
+          [ "switch" ]))
+
 module Create = struct
   module Source_with_original = struct
     type t = { source : Source.t; original : string }
 
-    let of_string s =
-      match Source.parse s with
-      | Ok source -> Ok { source; original = s }
-      | Error `Unknown -> Rresult.R.error_msgf "Invalid source: %S" s
+    let of_string original =
+      let open Let_syntax.Result in
+      let+ source = Source.parse original in
+      { source; original }
 
     let pp ppf { original; _ } = Format.pp_print_string ppf original
 
@@ -88,38 +127,6 @@ module Create = struct
          None
          (info ~doc:"Where to fetch the compiler." ~docv:"SOURCE" []))
 
-  let switch_name =
-    let open Cmdliner.Arg in
-    let conv = conv (Switch_name.parse, Switch_name.pp) in
-    value
-      (opt (some conv) None
-         (info ~docv:"SWITCH_NAME"
-            ~doc:
-              "Use this name for the switch. If omitted, a name is inferred \
-               from the source. This name is used as is by opam, so passing \
-               \".\" will create a local switch in the current directory."
-            [ "switch" ]))
-
-  let dry_run =
-    let open Cmdliner.Arg in
-    let info =
-      info
-        ~doc:
-          "Do not perform external commands. Print them and continue as if \
-           they worked."
-        [ "dry-run" ]
-    in
-    value (flag info)
-
-  let clients =
-    let open Let_syntax.Cmdliner in
-    let+ dry_run = dry_run in
-    let runner = if dry_run then Runner.dry_run else Runner.real in
-    let github_client =
-      if dry_run then Github_client.dry_run else Github_client.real
-    in
-    (runner, github_client)
-
   let man =
     [
       `S Cmdliner.Manpage.s_description;
@@ -132,6 +139,7 @@ module Create = struct
       `I
         ( "Github pull request (short form)",
           "#number (repo defaults to \"ocaml/ocaml\")" );
+      `I ("Directory", "path/to/sources");
     ]
 
   let term =
@@ -149,12 +157,54 @@ module Create = struct
   let command = (term, info)
 end
 
+module Reinstall = struct
+  let reinstall_mode =
+    let open Cmdliner.Arg in
+    value
+      (vflag Op.Full
+         [
+           ( Full,
+             info ~doc:"Perform a full reinstallation (default)." [ "full" ] );
+           ( Quick,
+             info ~doc:"Perform a quick reinstallation (unsafe)" [ "quick" ] );
+         ])
+
+  let term =
+    let open Let_syntax.Cmdliner in
+    let+ mode = reinstall_mode
+    and+ switch_name = switch_name
+    and+ runner, _github_client = clients in
+    Reinstall { mode; switch_name; runner }
+
+  let man =
+    [
+      `P "Reinstall the compiler will propagate the changes done to its source.";
+      `P "There are two ways to reinstall:";
+      `I
+        ( "Full (default)",
+          "Reinstall the compiler and all the packages in the switch. This can \
+           be slow but is always safe." );
+      `I
+        ( "Quick (unsafe)",
+          "Only reinstall the compiler. This is fast, but will break the \
+           switch if the way it compiles is modified for example." );
+    ]
+
+  let info =
+    let open Cmdliner.Term in
+    info ~man ~doc:"Reinstall the compiler" "reinstall"
+
+  let command = (term, info)
+end
+
 let default =
   let open Cmdliner.Term in
   (ret (pure (`Help (`Auto, None))), info "opam-compiler")
 
 let main () =
-  let result = Cmdliner.Term.eval_choice default [ Create.command ] in
+  let result =
+    Cmdliner.Term.eval_choice default [ Create.command; Reinstall.command ]
+  in
   (match result with
   | `Ok op -> eval op |> Rresult.R.failwith_error_msg
   | `Version -> ()
diff --git a/lib/import.ml b/lib/import.ml
index 4e7b987..b236df3 100644
--- a/lib/import.ml
+++ b/lib/import.ml
@@ -42,10 +42,12 @@ let pp_cmd ppf cmd =
   Bos.Cmd.to_list cmd |> List.map quote_if_needed |> String.concat " "
   |> Format.pp_print_string ppf
 
-type error = [ `Command_failed of Bos.Cmd.t | `Unknown ]
+type error = [ `Command_failed of Bos.Cmd.t | `Unknown | `No_compiler_sources ]
 
 let translate_error s =
   let open Rresult.R in
   reword_error (function
     | `Unknown -> msgf "%s" s
-    | `Command_failed cmd -> msgf "%s - command failed: %a" s pp_cmd cmd)
+    | `Command_failed cmd -> msgf "%s - command failed: %a" s pp_cmd cmd
+    | `No_compiler_sources ->
+        msgf "%s - switch is not linked to compiler sources" s)
diff --git a/lib/import.mli b/lib/import.mli
index 9187937..c4159bf 100644
--- a/lib/import.mli
+++ b/lib/import.mli
@@ -27,7 +27,7 @@ val pp_env : Format.formatter -> (string * string) list option -> unit
 
 val pp_cmd : Format.formatter -> Bos.Cmd.t -> unit
 
-type error = [ `Command_failed of Bos.Cmd.t | `Unknown ]
+type error = [ `Command_failed of Bos.Cmd.t | `Unknown | `No_compiler_sources ]
 
 val translate_error :
   string -> ('a, [< error ]) result -> ('a, [> Rresult.R.msg ]) result
diff --git a/lib/op.ml b/lib/op.ml
index 5ffaf02..4a60fa3 100644
--- a/lib/op.ml
+++ b/lib/op.ml
@@ -9,6 +9,36 @@ let try_ r ~if_command_failed =
       e
   | Error _ as e -> e
 
+let compiler_sources = "sources"
+
+let configure_command = "configure-command"
+
+let decode_using f x =
+  let open Let_syntax.Result in
+  let* ro = x in
+  match ro with
+  | None -> Ok None
+  | Some r -> (
+      match f r with Error _ -> Error `Unknown | Ok p -> Ok (Some p))
+
+let get_compiler_sources runner name =
+  Opam.get_variable runner name ~variable:compiler_sources
+  |> decode_using Fpath.of_string
+
+let set_compiler_sources runner name path =
+  Opam.set_variable runner name ~variable:compiler_sources
+    ~value:(Fpath.to_string path)
+
+let get_configure_command runner name =
+  Opam.get_variable runner name ~variable:configure_command
+  |> decode_using Bos.Cmd.of_string
+
+let set_configure_command runner name command =
+  Opam.set_variable runner name ~variable:configure_command
+    ~value:(Format.asprintf "%a" pp_cmd command)
+
+let iter ~f = function None -> Ok () | Some x -> f x
+
 let create runner github_client source switch_name ~configure_command =
   let switch_name =
     match switch_name with
@@ -23,7 +53,12 @@ let create runner github_client source switch_name ~configure_command =
      try_ (Opam.pin_add runner switch_name url ~configure_command)
        ~if_command_failed:(fun () -> Opam.remove_switch runner switch_name)
    in
-   Opam.set_base runner switch_name)
+   let* () = Opam.set_base runner switch_name in
+   match Source.compiler_sources source with
+   | None -> Ok ()
+   | Some sources ->
+       let* () = set_compiler_sources runner switch_name sources in
+       iter configure_command ~f:(set_configure_command runner switch_name))
   |> translate_error "Cannot create switch"
 
 type reinstall_mode = Quick | Full
@@ -32,8 +67,17 @@ let reinstall_packages_if_needed runner = function
   | Quick -> Ok ()
   | Full -> Opam.reinstall_packages runner
 
-let reinstall runner mode ~configure_command =
+let unwrap_compiler_sources = function
+  | None -> Error `No_compiler_sources
+  | Some v -> Ok v
+
+let reinstall runner mode ~name =
   let open Let_syntax.Result in
-  (let* () = Opam.reinstall_compiler runner ~configure_command in
+  (let* compiler_sources_opt = get_compiler_sources runner name in
+   let* compiler_sources = unwrap_compiler_sources compiler_sources_opt in
+   let* configure_command = get_configure_command runner name in
+   let* () =
+     Opam.reinstall_compiler runner ~compiler_sources ~configure_command
+   in
    reinstall_packages_if_needed runner mode)
   |> translate_error "Could not reinstall"
diff --git a/lib/op.mli b/lib/op.mli
index 89ede15..904c9e2 100644
--- a/lib/op.mli
+++ b/lib/op.mli
@@ -11,5 +11,5 @@ type reinstall_mode = Quick | Full
 val reinstall :
   Runner.t ->
   reinstall_mode ->
-  configure_command:Bos.Cmd.t option ->
+  name:Switch_name.t option ->
   (unit, [> Rresult.R.msg ]) result
diff --git a/lib/opam.ml b/lib/opam.ml
index bd12d50..bd39f33 100644
--- a/lib/opam.ml
+++ b/lib/opam.ml
@@ -64,22 +64,22 @@ let set_base runner name =
 let update runner name =
   run_opam runner [ A "update"; switch name; ocaml_variants ]
 
-let reinstall_configure runner ~configure_command =
+let reinstall_configure runner ~configure_command ~compiler_sources =
   let open Let_syntax.Result in
   let* prefix = run_out_opam runner [ A "config"; A "var"; A "prefix" ] in
   let base_command =
     Option.value configure_command ~default:Bos.Cmd.(v "./configure")
   in
   let command = Bos.Cmd.(base_command % "--prefix" % prefix) in
-  Runner.run runner command
+  Runner.run ~chdir:compiler_sources runner command
 
-let reinstall_compiler runner ~configure_command =
+let reinstall_compiler runner ~compiler_sources ~configure_command =
   let open Let_syntax.Result in
   let make = Bos.Cmd.(v "make") in
   let make_install = Bos.Cmd.(v "make" % "install") in
-  let* () = reinstall_configure runner ~configure_command in
-  let* () = Runner.run runner make in
-  Runner.run runner make_install
+  let* () = reinstall_configure runner ~compiler_sources ~configure_command in
+  let* () = Runner.run ~chdir:compiler_sources runner make in
+  Runner.run ~chdir:compiler_sources runner make_install
 
 let reinstall_packages runner =
   run_opam runner
@@ -88,3 +88,28 @@ let reinstall_packages runner =
 let remove_switch runner name =
   run_opam runner
     [ A "switch"; A "remove"; A "--yes"; A (Switch_name.to_string name) ]
+
+module Var = struct
+  let prefix = "compiler-"
+
+  let to_string var = prefix ^ var
+
+  let get runner name ~variable =
+    let open Let_syntax.Result in
+    let pattern = Format.sprintf "%%{%s}%%" (to_string variable) in
+    let switch =
+      match name with Some name -> L [ switch name ] | None -> L []
+    in
+    let+ output =
+      run_out_opam runner [ A "config"; switch; A "expand"; A pattern ]
+    in
+    if String.equal output "" then None else Some output
+
+  let set runner name ~variable ~value =
+    run_opam runner
+      [ A "config"; switch name; A "set"; A (to_string variable); A value ]
+end
+
+let get_variable = Var.get
+
+let set_variable = Var.set
diff --git a/lib/opam.mli b/lib/opam.mli
index 02d4f38..847d4fa 100644
--- a/lib/opam.mli
+++ b/lib/opam.mli
@@ -15,8 +15,24 @@ val set_base : Runner.t -> Switch_name.t -> (unit, error) result
 val update : Runner.t -> Switch_name.t -> (unit, error) result
 
 val reinstall_compiler :
-  Runner.t -> configure_command:Bos.Cmd.t option -> (unit, error) result
+  Runner.t ->
+  compiler_sources:Fpath.t ->
+  configure_command:Bos.Cmd.t option ->
+  (unit, error) result
 
 val reinstall_packages : Runner.t -> (unit, error) result
 
 val remove_switch : Runner.t -> Switch_name.t -> (unit, error) result
+
+val get_variable :
+  Runner.t ->
+  Switch_name.t option ->
+  variable:string ->
+  (string option, error) result
+
+val set_variable :
+  Runner.t ->
+  Switch_name.t ->
+  variable:string ->
+  value:string ->
+  (unit, error) result
diff --git a/lib/runner.ml b/lib/runner.ml
index 3a46ef8..95153cb 100644
--- a/lib/runner.ml
+++ b/lib/runner.ml
@@ -4,7 +4,10 @@ type run_error = [ `Command_failed of Bos.Cmd.t | `Unknown ]
 
 type t = {
   run :
-    ?extra_env:(string * string) list -> Bos.Cmd.t -> (unit, run_error) result;
+    ?extra_env:(string * string) list ->
+    ?chdir:Fpath.t ->
+    Bos.Cmd.t ->
+    (unit, run_error) result;
   run_out :
     ?extra_env:(string * string) list -> Bos.Cmd.t -> (string, run_error) result;
 }
@@ -22,10 +25,18 @@ module Real = struct
         let seq = List.to_seq l in
         Some (Astring.String.Map.add_seq seq cur)
 
-  let run ?extra_env cmd =
+  let with_chdir ~f = function
+    | None -> f ()
+    | Some dir ->
+        let open Let_syntax.Result in
+        let* r = Bos.OS.Dir.with_current dir f () in
+        r
+
+  let run ?extra_env ?chdir cmd =
     let open Let_syntax.Result in
     let* env = explicit_env extra_env in
-    Bos.OS.Cmd.in_null |> Bos.OS.Cmd.run_in ?env cmd
+    with_chdir chdir ~f:(fun () ->
+        Bos.OS.Cmd.in_null |> Bos.OS.Cmd.run_in ?env cmd)
     |> Rresult.R.reword_error (fun _ -> `Command_failed cmd)
 
   let run_out ?extra_env cmd =
@@ -33,7 +44,7 @@ module Real = struct
     let* env = explicit_env extra_env in
     Bos.OS.Cmd.run_out ?env cmd
     |> Bos.OS.Cmd.to_string
-    |> Rresult.R.reword_error (fun _ -> `Unknown)
+    |> Rresult.R.reword_error (fun _ -> `Command_failed cmd)
 end
 
 let real =
@@ -41,13 +52,17 @@ let real =
   { run; run_out }
 
 module Dry_run = struct
-  let run ?extra_env cmd =
-    Format.printf "Run: %a%a\n" pp_env extra_env pp_cmd cmd;
+  let pp_chdir ppf = function
+    | None -> ()
+    | Some p -> Format.fprintf ppf "cd %a && " Fpath.pp p
+
+  let run ?extra_env ?chdir cmd =
+    Format.printf "Run: %a%a%a\n" pp_env extra_env pp_chdir chdir pp_cmd cmd;
     Ok ()
 
   let run_out ?extra_env cmd =
     Format.printf "Run_out: %a%a\n" pp_env extra_env pp_cmd cmd;
-    Ok "output"
+    Format.kasprintf Rresult.R.ok "$(%a%a)" pp_env extra_env pp_cmd cmd
 end
 
 let dry_run =
@@ -59,5 +74,7 @@ let run_out t ?extra_env cmd =
     : (_, run_error) result
     :> (_, [> run_error ]) result)
 
-let run t ?extra_env cmd =
-  (t.run ?extra_env cmd : (_, run_error) result :> (_, [> run_error ]) result)
+let run t ?extra_env ?chdir cmd =
+  (t.run ?extra_env ?chdir cmd
+    : (_, run_error) result
+    :> (_, [> run_error ]) result)
diff --git a/lib/runner.mli b/lib/runner.mli
index 9bd4351..afeac36 100644
--- a/lib/runner.mli
+++ b/lib/runner.mli
@@ -1,6 +1,7 @@
 type t = {
   run :
     ?extra_env:(string * string) list ->
+    ?chdir:Fpath.t ->
     Bos.Cmd.t ->
     (unit, [ `Command_failed of Bos.Cmd.t | `Unknown ]) result;
   run_out :
@@ -16,6 +17,7 @@ val dry_run : t
 val run :
   t ->
   ?extra_env:(string * string) list ->
+  ?chdir:Fpath.t ->
   Bos.Cmd.t ->
   (unit, [> `Command_failed of Bos.Cmd.t | `Unknown ]) result
 
diff --git a/lib/source.ml b/lib/source.ml
index 89bd09d..e38259d 100644
--- a/lib/source.ml
+++ b/lib/source.ml
@@ -1,6 +1,9 @@
 open! Import
 
-type t = Github_branch of Branch.t | Github_PR of Pull_request.t
+type t =
+  | Github_branch of Branch.t
+  | Github_PR of Pull_request.t
+  | Directory of Fpath.t
 
 let github_pr pr = Github_PR pr
 
@@ -27,16 +30,23 @@ let parse_as_branch s =
 
 let parse_as_pr s = Option.map github_pr (Pull_request.parse s)
 
+let parse_as_directory s =
+  match Fpath.of_string s with
+  | Ok p when Fpath.is_abs p -> Ok (Directory p)
+  | Ok _ -> Rresult.R.error_msgf "Source should be an absolute directory"
+  | Error _ -> Rresult.R.error_msgf "Invalid path: %S" s
+
 let parse s =
-  match parse_as_branch s with
-  | Some r -> Ok r
-  | None -> (
-      match parse_as_pr s with Some r -> Ok r | None -> Error `Unknown)
+  let ( let/ ) x k = match x with Some r -> Ok r | None -> k () in
+  let/ () = parse_as_branch s in
+  let/ () = parse_as_pr s in
+  parse_as_directory s
 
 let pp ppf = function
   | Github_branch branch ->
       Format.fprintf ppf "Github_branch %a" Branch.pp branch
   | Github_PR pr -> Format.fprintf ppf "Github_PR %a" Pull_request.pp pr
+  | Directory p -> Format.fprintf ppf "Directory %a" Fpath.pp p
 
 let raw_switch_name source =
   match source with
@@ -44,6 +54,7 @@ let raw_switch_name source =
       Format.asprintf "%s/%s:%s" user repo branch
   | Github_PR { user; repo; number } ->
       Format.asprintf "%s/%s#%d" user repo number
+  | Directory p -> Format.asprintf "%a" Fpath.pp p
 
 let global_switch_name source =
   Switch_name.escape_string (raw_switch_name source)
@@ -59,6 +70,7 @@ let extra_description source (client : Github_client.t) =
       let open Let_syntax.Option in
       let+ { title; _ } = Result.to_option (client.pr_info pr) in
       title
+  | Directory _ -> None
 
 let switch_description source client =
   Format.asprintf "[opam-compiler] %s%a" (raw_switch_name source)
@@ -72,5 +84,11 @@ let switch_target source github_client =
       let open Let_syntax.Result in
       let+ { source_branch; _ } = Github_client.pr_info github_client pr in
       Branch.git_url source_branch
+  | Directory path -> Ok (Format.asprintf "file://%a" Fpath.pp path)
 
 let equal (x : t) y = x = y
+
+let compiler_sources = function
+  | Github_branch _ -> None
+  | Github_PR _ -> None
+  | Directory p -> Some p
diff --git a/lib/source.mli b/lib/source.mli
index 70a952d..fb4ce8e 100644
--- a/lib/source.mli
+++ b/lib/source.mli
@@ -1,4 +1,7 @@
-type t = Github_branch of Branch.t | Github_PR of Pull_request.t
+type t =
+  | Github_branch of Branch.t
+  | Github_PR of Pull_request.t
+  | Directory of Fpath.t
 
 val switch_target : t -> Github_client.t -> (string, [> `Unknown ]) result
 
@@ -10,4 +13,6 @@ val pp : Format.formatter -> t -> unit
 
 val equal : t -> t -> bool
 
-val parse : string -> (t, [ `Unknown ]) result
+val parse : string -> (t, Rresult.R.msg) result
+
+val compiler_sources : t -> Fpath.t option
diff --git a/lib/switch_name.ml b/lib/switch_name.ml
index a0ecd5d..3987331 100644
--- a/lib/switch_name.ml
+++ b/lib/switch_name.ml
@@ -8,8 +8,17 @@ let to_string s = s
 
 let invalid_chars = [ '/'; ':'; '#' ]
 
-let escape_string =
-  String.map (fun c -> if List.mem c invalid_chars then '-' else c)
+let strip_leading_dashes =
+  let open Re in
+  let re = compile (seq [ bos; rep1 (char '-') ]) in
+  replace_string re ~by:""
+
+let remove_invalid_chars =
+  let open Re in
+  let re = compile (alt (List.map char invalid_chars)) in
+  replace_string re ~by:"-"
+
+let escape_string s = s |> remove_invalid_chars |> strip_leading_dashes
 
 let parse s =
   if List.exists (fun c -> String.contains s c) invalid_chars then
diff --git a/test/cram/create.t b/test/cram/create.t
index f2f98f6..c5cb703 100644
--- a/test/cram/create.t
+++ b/test/cram/create.t
@@ -19,6 +19,22 @@ Github PR numbers are also accepted:
   Run: OPAMCLI=2.0 opam pin add --switch ocaml-ocaml-1234 --yes ocaml-variants git+https://github.com/user-ocaml-ocaml-1234/repo-ocaml-ocaml-1234#branch-ocaml-ocaml-1234
   Run: OPAMCLI=2.0 opam switch set-base --switch ocaml-ocaml-1234 ocaml-variants
 
+Directories are supported.
+
+  $ opam-compiler create --dry-run /home/me/ocaml
+  Run: OPAMCLI=2.0 opam switch create home-me-ocaml --empty --description "[opam-compiler] /home/me/ocaml"
+  Run: OPAMCLI=2.0 opam pin add --switch home-me-ocaml --yes ocaml-variants file:///home/me/ocaml
+  Run: OPAMCLI=2.0 opam switch set-base --switch home-me-ocaml ocaml-variants
+  Run: OPAMCLI=2.0 opam config --switch home-me-ocaml set compiler-sources /home/me/ocaml
+
+Directories need to be absolute paths.
+
+  $ opam-compiler create --dry-run somewhere
+  opam-compiler: SOURCE argument: Source should be an absolute directory
+  Usage: opam-compiler create [OPTION]... SOURCE
+  Try `opam-compiler create --help' or `opam-compiler --help' for more information.
+  [124]
+
 An explicit configure step can be passed:
 
   $ opam-compiler create --dry-run USER/REPO:BRANCH --configure-command "./configure --enable-x"
diff --git a/test/cram/reinstall.t b/test/cram/reinstall.t
new file mode 100644
index 0000000..e147af0
--- /dev/null
+++ b/test/cram/reinstall.t
@@ -0,0 +1,40 @@
+  $ opam-compiler reinstall --dry-run
+  Run_out: OPAMCLI=2.0 opam config expand %{compiler-sources}%
+  Run_out: OPAMCLI=2.0 opam config expand %{compiler-configure-command}%
+  Run_out: OPAMCLI=2.0 opam config var prefix
+  Run: cd $(OPAMCLI=2.0 opam config expand %{compiler-sources}%) && $(OPAMCLI=2.0 opam config expand %{compiler-configure-command}%) --prefix "$(OPAMCLI=2.0 opam config var prefix)"
+  Run: cd $(OPAMCLI=2.0 opam config expand %{compiler-sources}%) && make
+  Run: cd $(OPAMCLI=2.0 opam config expand %{compiler-sources}%) && make install
+  Run: OPAMCLI=2.0 opam reinstall --assume-built --working-dir ocaml-variants
+
+Quick can be passed:
+
+  $ opam-compiler reinstall --dry-run --quick
+  Run_out: OPAMCLI=2.0 opam config expand %{compiler-sources}%
+  Run_out: OPAMCLI=2.0 opam config expand %{compiler-configure-command}%
+  Run_out: OPAMCLI=2.0 opam config var prefix
+  Run: cd $(OPAMCLI=2.0 opam config expand %{compiler-sources}%) && $(OPAMCLI=2.0 opam config expand %{compiler-configure-command}%) --prefix "$(OPAMCLI=2.0 opam config var prefix)"
+  Run: cd $(OPAMCLI=2.0 opam config expand %{compiler-sources}%) && make
+  Run: cd $(OPAMCLI=2.0 opam config expand %{compiler-sources}%) && make install
+
+Full will reinstall opam packages (and is the default):
+
+  $ opam-compiler reinstall --dry-run --full
+  Run_out: OPAMCLI=2.0 opam config expand %{compiler-sources}%
+  Run_out: OPAMCLI=2.0 opam config expand %{compiler-configure-command}%
+  Run_out: OPAMCLI=2.0 opam config var prefix
+  Run: cd $(OPAMCLI=2.0 opam config expand %{compiler-sources}%) && $(OPAMCLI=2.0 opam config expand %{compiler-configure-command}%) --prefix "$(OPAMCLI=2.0 opam config var prefix)"
+  Run: cd $(OPAMCLI=2.0 opam config expand %{compiler-sources}%) && make
+  Run: cd $(OPAMCLI=2.0 opam config expand %{compiler-sources}%) && make install
+  Run: OPAMCLI=2.0 opam reinstall --assume-built --working-dir ocaml-variants
+
+Switch name can be passed explicitly:
+
+  $ opam-compiler reinstall --dry-run --switch NAME
+  Run_out: OPAMCLI=2.0 opam config --switch NAME expand %{compiler-sources}%
+  Run_out: OPAMCLI=2.0 opam config --switch NAME expand %{compiler-configure-command}%
+  Run_out: OPAMCLI=2.0 opam config var prefix
+  Run: cd $(OPAMCLI=2.0 opam config --switch NAME expand %{compiler-sources}%) && $(OPAMCLI=2.0 opam config --switch NAME expand %{compiler-configure-command}%) --prefix "$(OPAMCLI=2.0 opam config var prefix)"
+  Run: cd $(OPAMCLI=2.0 opam config --switch NAME expand %{compiler-sources}%) && make
+  Run: cd $(OPAMCLI=2.0 opam config --switch NAME expand %{compiler-sources}%) && make install
+  Run: OPAMCLI=2.0 opam reinstall --assume-built --working-dir ocaml-variants
diff --git a/test/opam/client.ml b/test/opam/client.ml
index 4bc00bf..68d44c2 100755
--- a/test/opam/client.ml
+++ b/test/opam/client.ml
@@ -1,6 +1,12 @@
 open Opam_compiler
 open! Import
 
+let pp_option pp ppf = function
+  | None -> Format.fprintf ppf "None"
+  | Some x -> Format.fprintf ppf "Some %a" pp x
+
+let pp_string ppf s = Format.fprintf ppf "%S" s
+
 let () =
   let open Let_syntax.Result in
   let runner = Runner.real in
@@ -14,4 +20,23 @@ let () =
       (let* name = Switch_name.parse name in
        translate_error "remove" (Opam.remove_switch runner name))
       |> Rresult.R.failwith_error_msg
+  | [| _; "get-var"; name; variable |] ->
+      (let* name = Switch_name.parse name in
+       let+ r =
+         translate_error "get-var"
+           (Opam.get_variable runner (Some name) ~variable)
+       in
+       Format.printf "get-var: %a\n" (pp_option pp_string) r)
+      |> Rresult.R.failwith_error_msg
+  | [| _; "set-var"; name; variable; value |] ->
+      (let* name = Switch_name.parse name in
+       translate_error "set-var"
+         (Opam.set_variable runner name ~variable ~value))
+      |> Rresult.R.failwith_error_msg
+  | [| _; "reinstall-compiler"; compiler_sources_s |] ->
+      (let* compiler_sources = Fpath.of_string compiler_sources_s in
+       translate_error "reinstall-compiler"
+         (Opam.reinstall_compiler runner ~compiler_sources
+            ~configure_command:None))
+      |> Rresult.R.failwith_error_msg
   | _ -> assert false
diff --git a/test/unit/mock.ml b/test/unit/mock.ml
index 76e8954..2f6014e 100644
--- a/test/unit/mock.ml
+++ b/test/unit/mock.ml
@@ -1,13 +1,13 @@
 type ('a, 'b) expectation = 'a * 'b
 
+let expect expected ~and_return:return_value = (expected, return_value)
+
 type ('a, 'b) t = {
   testable : 'a Alcotest.testable;
   loc : string;
   mutable expectations : ('a, 'b) expectation list;
 }
 
-let expect expected ~and_return:return_value = (expected, return_value)
-
 let call t got =
   match t.expectations with
   | [] ->
diff --git a/test/unit/test.ml b/test/unit/test.ml
index ff26d7b..2fc11bf 100644
--- a/test/unit/test.ml
+++ b/test/unit/test.ml
@@ -1,3 +1,3 @@
-let all_tests = Test_op.tests @ Test_source.tests
+let all_tests = Test_op.tests @ Test_source.tests @ Test_switch_name.tests
 
 let () = Alcotest.run "opam-compiler" all_tests
diff --git a/test/unit/test_op.ml b/test/unit/test_op.ml
index 8cc6984..8ccb38e 100644
--- a/test/unit/test_op.ml
+++ b/test/unit/test_op.ml
@@ -1,5 +1,5 @@
 open Opam_compiler
-open Import
+open! Import
 
 let msg = Alcotest.testable Rresult.R.pp_msg ( = )
 
@@ -8,6 +8,12 @@ let cmd = Alcotest.testable pp_cmd Bos.Cmd.equal
 type call_run = {
   command : Bos.Cmd.t;
   extra_env : (string * string) list option;
+  chdir : Fpath.t option;
+}
+
+type call_run_out = {
+  command : Bos.Cmd.t;
+  extra_env : (string * string) list option;
 }
 
 let alcotest_contramap (type a) ~f t =
@@ -19,8 +25,9 @@ let alcotest_contramap (type a) ~f t =
 let mock_runner loc expectations =
   let call_run_testable =
     alcotest_contramap
-      Alcotest.(pair cmd (option (list (pair string string))))
-      ~f:(fun { command; extra_env } -> (command, extra_env))
+      Alcotest.(
+        triple cmd (option (list (pair string string))) (option (module Fpath)))
+      ~f:(fun { command; extra_env; chdir } -> (command, extra_env, chdir))
   in
   let call_run_out_testable =
     alcotest_contramap
@@ -30,7 +37,7 @@ let mock_runner loc expectations =
   let call_run, call_run_out, check =
     Mock.create2 call_run_testable call_run_out_testable loc expectations
   in
-  let run ?extra_env command = call_run { command; extra_env } in
+  let run ?extra_env ?chdir command = call_run { command; extra_env; chdir } in
   let run_out ?extra_env command = call_run_out { command; extra_env } in
   let runner = { Runner.run; run_out } in
   (runner, check)
@@ -61,13 +68,17 @@ let create_tests =
       v "opam" % "switch" % "create" % "USER-REPO-BRANCH" % "--empty"
       % "--description" % "[opam-compiler] USER/REPO:BRANCH")
   in
-  let create_call = { command = create_cmd; extra_env = opam_cli_env } in
+  let create_call =
+    { command = create_cmd; extra_env = opam_cli_env; chdir = None }
+  in
   let pin_add_cmd =
     Bos.Cmd.(
       v "opam" % "pin" % "add" % "--switch" % "USER-REPO-BRANCH" % "--yes"
       % "ocaml-variants" % "git+https://github.com/USER/REPO#BRANCH")
   in
-  let pin_add_call = { command = pin_add_cmd; extra_env = opam_cli_env } in
+  let pin_add_call =
+    { command = pin_add_cmd; extra_env = opam_cli_env; chdir = None }
+  in
   [
     test "create: create fails with unknown error"
       [ Mock.expect create_call ~and_return:(Error `Unknown) ]
@@ -83,6 +94,7 @@ let create_tests =
               Bos.Cmd.(
                 v "opam" % "switch" % "remove" % "--yes" % "USER-REPO-BRANCH");
             extra_env = opam_cli_env;
+            chdir = None;
           }
           ~and_return:(Ok ());
       ]
@@ -94,78 +106,66 @@ let create_tests =
   ]
 
 let reinstall_tests =
-  let test name mode configure_command expectations ~expected =
+  let test name ~expectations ~expected =
     ( name,
       `Quick,
       fun () ->
         let runner, check = mock_runner __LOC__ expectations in
-        let got = Op.reinstall runner mode ~configure_command in
+        let got = Op.reinstall runner Quick ~name:None in
         Alcotest.check Alcotest.(result unit msg) __LOC__ expected got;
         check () )
   in
-  let expect_run ~command ~extra_env ~and_return =
-    Either.Left (Mock.expect { command; extra_env } ~and_return)
+  let expect_run ~command ~extra_env ~chdir ~and_return =
+    Either.Left (Mock.expect { command; extra_env; chdir } ~and_return)
   in
   let expect_run_out ~command ~extra_env ~and_return =
     Either.Right (Mock.expect { command; extra_env } ~and_return)
   in
   [
-    test "reinstall (quick)" Quick None
-      [
-        expect_run_out
-          ~command:Bos.Cmd.(v "opam" % "config" % "var" % "prefix")
-          ~extra_env:opam_cli_env ~and_return:(Ok "PREFIX");
-        expect_run
-          ~command:Bos.Cmd.(v "./configure" % "--prefix" % "PREFIX")
-          ~extra_env:None ~and_return:(Ok ());
-        expect_run
-          ~command:Bos.Cmd.(v "make")
-          ~extra_env:None ~and_return:(Ok ());
-        expect_run
-          ~command:Bos.Cmd.(v "make" % "install")
-          ~extra_env:None ~and_return:(Ok ());
-      ]
-      ~expected:(Ok ());
-    test "reinstall (full)" Full None
-      [
-        expect_run_out
-          ~command:Bos.Cmd.(v "opam" % "config" % "var" % "prefix")
-          ~extra_env:opam_cli_env ~and_return:(Ok "PREFIX");
-        expect_run
-          ~command:Bos.Cmd.(v "./configure" % "--prefix" % "PREFIX")
-          ~extra_env:None ~and_return:(Ok ());
-        expect_run
-          ~command:Bos.Cmd.(v "make")
-          ~extra_env:None ~and_return:(Ok ());
-        expect_run
-          ~command:Bos.Cmd.(v "make" % "install")
-          ~extra_env:None ~and_return:(Ok ());
-        expect_run
-          ~command:
-            Bos.Cmd.(
-              v "opam" % "reinstall" % "--assume-built" % "--working-dir"
-              % "ocaml-variants")
-          ~extra_env:opam_cli_env ~and_return:(Ok ());
-      ]
-      ~expected:(Ok ());
-    test "reinstall (different configure command)" Quick
-      (Some Bos.Cmd.(v "./configure" % "--enable-something"))
-      [
-        expect_run_out
-          ~command:Bos.Cmd.(v "opam" % "config" % "var" % "prefix")
-          ~extra_env:opam_cli_env ~and_return:(Ok "PREFIX");
-        expect_run
-          ~command:
-            Bos.Cmd.(
-              v "./configure" % "--enable-something" % "--prefix" % "PREFIX")
-          ~extra_env:None ~and_return:(Ok ());
-        expect_run
-          ~command:Bos.Cmd.(v "make")
-          ~extra_env:None ~and_return:(Ok ());
-        expect_run
-          ~command:Bos.Cmd.(v "make" % "install")
-          ~extra_env:None ~and_return:(Ok ());
-      ]
+    test "reinstall: switch does not have sources"
+      ~expectations:
+        [
+          expect_run_out
+            ~command:
+              Bos.Cmd.(v "opam" % "config" % "expand" % "%{compiler-sources}%")
+            ~extra_env:opam_cli_env ~and_return:(Ok "");
+        ]
+      ~expected:
+        (Error
+           (`Msg
+             "Could not reinstall - switch is not linked to compiler sources"));
+    test "reinstall: switch does not have a configure command sources"
+      ~expectations:
+        [
+          expect_run_out
+            ~command:
+              Bos.Cmd.(v "opam" % "config" % "expand" % "%{compiler-sources}%")
+            ~extra_env:opam_cli_env ~and_return:(Ok "COMPILER-SOURCES");
+          expect_run_out
+            ~command:
+              Bos.Cmd.(
+                v "opam" % "config" % "expand"
+                % "%{compiler-configure-command}%")
+            ~extra_env:opam_cli_env ~and_return:(Ok "");
+          expect_run_out
+            ~command:Bos.Cmd.(v "opam" % "config" % "var" % "prefix")
+            ~extra_env:opam_cli_env ~and_return:(Ok "PREFIX");
+          expect_run
+            ~command:Bos.Cmd.(v "./configure" % "--prefix" % "PREFIX")
+            ~extra_env:None
+            ~chdir:(Some (Fpath.v "COMPILER-SOURCES"))
+            ~and_return:(Ok ());
+          expect_run
+            ~command:Bos.Cmd.(v "make")
+            ~extra_env:None
+            ~chdir:(Some (Fpath.v "COMPILER-SOURCES"))
+            ~and_return:(Ok ());
+          expect_run
+            ~command:Bos.Cmd.(v "make" % "install")
+            ~extra_env:None
+            ~chdir:(Some (Fpath.v "COMPILER-SOURCES"))
+            ~and_return:(Ok ());
+        ]
       ~expected:(Ok ());
   ]
 
diff --git a/test/unit/test_source.ml b/test/unit/test_source.ml
index 170c7e3..7ca2bed 100644
--- a/test/unit/test_source.ml
+++ b/test/unit/test_source.ml
@@ -5,14 +5,17 @@ let error =
   let equal_error = ( = ) in
   Alcotest.testable pp_error equal_error
 
+let msg = Alcotest.testable Rresult.R.pp_msg ( = )
+
 let parse_tests =
   let test name s expected =
     ( name,
       `Quick,
       fun () ->
         let got = Source.parse s in
-        Alcotest.(check (result (module Source) error) __LOC__ expected got) )
+        Alcotest.(check (result (module Source) msg) __LOC__ expected got) )
   in
+  let fpath_exn s = Fpath.of_string s |> Rresult.R.failwith_error_msg in
   [
     test "full branch syntax" "user/repo:branch"
       (Ok (Github_branch { user = "user"; repo = "repo"; branch = "branch" }));
@@ -26,13 +29,20 @@ let parse_tests =
       (Ok (Github_PR { user = "user"; repo = "repo"; number = 1234 }));
     test "defaults to main repo" "#1234"
       (Ok (Github_PR { user = "ocaml"; repo = "ocaml"; number = 1234 }));
-    test "something that does not parse" "a-random-string" (Error `Unknown);
+    test "something that does not parse" ""
+      (Rresult.R.error_msg "Invalid path: \"\"");
     test "users can have dashes" "user-with-dashes/repo#1234"
       (Ok
          (Github_PR { user = "user-with-dashes"; repo = "repo"; number = 1234 }));
     test "repos can have dashes" "user/repo-with-dashes#1234"
       (Ok
          (Github_PR { user = "user"; repo = "repo-with-dashes"; number = 1234 }));
+    test "relative directory" "."
+      (Rresult.R.error_msg "Source should be an absolute directory");
+    test "absolute directory" "/home/me/ocaml"
+      (Ok (Directory (fpath_exn "/home/me/ocaml")));
+    test "invalid directory name" "/home\x00"
+      (Rresult.R.error_msg "Invalid path: \"/home\\000\"");
   ]
 
 let switch_target_tests =
diff --git a/test/unit/test_switch_name.ml b/test/unit/test_switch_name.ml
new file mode 100644
index 0000000..23af56a
--- /dev/null
+++ b/test/unit/test_switch_name.ml
@@ -0,0 +1,20 @@
+open Opam_compiler
+
+let switch_name_escape_string_tests =
+  let test ~name s ~expected =
+    ( name,
+      `Quick,
+      fun () ->
+        let got = Switch_name.escape_string s in
+        let expected = Switch_name.of_string_exn expected in
+        Alcotest.check (module Switch_name) __LOC__ expected got )
+  in
+  [
+    test ~name:"slash is escaped" "a/b" ~expected:"a-b";
+    test ~name:"colon is escaped" "a:b" ~expected:"a-b";
+    test ~name:"hash is escaped" "a#b" ~expected:"a-b";
+    test ~name:"leading dashes are removed" "/home/me/ocaml"
+      ~expected:"home-me-ocaml";
+  ]
+
+let tests = [ ("Switch_name escape_string", switch_name_escape_string_tests) ]
diff --git a/test/unit/test_switch_name.mli b/test/unit/test_switch_name.mli
new file mode 100644
index 0000000..c3be591
--- /dev/null
+++ b/test/unit/test_switch_name.mli
@@ -0,0 +1 @@
+val tests : unit Alcotest.test list