diff --git a/CHANGES.md b/CHANGES.md
index b6aceb20..56e01632 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -1,6 +1,6 @@
 ## unreleased
 
-- `wat2wasm` emit wasm files in same dir as wat files 
+- add `--output` option to `wat2wasm`, `wasm2wat` and `opt` cmd
 - add `--emit-file` option to `wasm2wat` to emit .wat files
 - adds flags `--fail-on-trap-only` and `fail-on-assertion-only`
 - parameterize the `Thread` module on the symbolic memory and the `Choice_monad` module on a Thread
diff --git a/example/opt/README.md b/example/opt/README.md
index eac22663..0dff811b 100644
--- a/example/opt/README.md
+++ b/example/opt/README.md
@@ -377,7 +377,7 @@ OPTIONS
            debug mode
 
        -o FILE, --output=FILE
-           wat
+           Write output to a file.
 
        -u, --unsafe
            skip typechecking pass
diff --git a/example/wasm2wat/README.md b/example/wasm2wat/README.md
index 3a8474f9..c5eac4f8 100644
--- a/example/wasm2wat/README.md
+++ b/example/wasm2wat/README.md
@@ -31,10 +31,10 @@ SYNOPSIS
 
 OPTIONS
        --emit-file
-           emit (.wat) files from corresponding (.wasm) files
+           Emit (.wat) files from corresponding (.wasm) files.
 
        -o FILE, --output=FILE
-           wasm
+           Write output to a file.
 
 COMMON OPTIONS
        --help[=FMT] (default=auto)
diff --git a/example/wat2wasm/README.md b/example/wat2wasm/README.md
index 3877b02f..57b5c744 100644
--- a/example/wat2wasm/README.md
+++ b/example/wat2wasm/README.md
@@ -41,7 +41,7 @@ OPTIONS
            debug mode
 
        -o FILE, --output=FILE
-           wat
+           Write output to a file.
 
        --optimize
            optimize mode
diff --git a/src/bin/owi.ml b/src/bin/owi.ml
index dfc9e1c6..078bfa25 100644
--- a/src/bin/owi.ml
+++ b/src/bin/owi.ml
@@ -39,13 +39,13 @@ let files =
   let f = existing_non_dir_file in
   Cmdliner.Arg.(value & pos_all f [] (info [] ~doc))
 
-let sourcefile ty =
-  let doc = Fmt.str "%s source file" ty in
+let sourcefile =
+  let doc = "source file" in
   let f = existing_non_dir_file in
   Cmdliner.Arg.(required & pos 0 (some f) None (info [] ~doc))
 
-let outfile ty =
-  let doc = Fmt.str "%s" ty in
+let outfile =
+  let doc = "Write output to a file." in
   let string_to_path =
     Cmdliner.Arg.conv ~docv:"FILE" (Fpath.of_string, Fpath.pp)
   in
@@ -54,8 +54,8 @@ let outfile ty =
     & opt (some string_to_path) None
     & info [ "o"; "output" ] ~docv:"FILE" ~doc )
 
-let emit_files =
-  let doc = "emit (.wat) files from corresponding (.wasm) files" in
+let emit_file =
+  let doc = "Emit (.wat) files from corresponding (.wasm) files." in
   Cmdliner.Arg.(value & flag & info [ "emit-file" ] ~doc)
 
 let no_exhaustion =
@@ -196,8 +196,7 @@ let opt_cmd =
     let man = [] @ shared_man in
     Cmd.info "opt" ~version ~doc ~sdocs ~man
   in
-  Cmd.v info
-    Term.(const Cmd_opt.cmd $ debug $ unsafe $ sourcefile "wat" $ outfile "wat")
+  Cmd.v info Term.(const Cmd_opt.cmd $ debug $ unsafe $ sourcefile $ outfile)
 
 let run_cmd =
   let open Cmdliner in
@@ -265,9 +264,7 @@ let wasm2wat_cmd =
     let man = [] @ shared_man in
     Cmd.info "wasm2wat" ~version ~doc ~sdocs ~man
   in
-  Cmd.v info
-    Term.(
-      const Cmd_wasm2wat.cmd $ sourcefile "wasm" $ emit_files $ outfile "wasm" )
+  Cmd.v info Term.(const Cmd_wasm2wat.cmd $ sourcefile $ emit_file $ outfile)
 
 let wat2wasm_cmd =
   let open Cmdliner in
@@ -280,8 +277,8 @@ let wat2wasm_cmd =
   in
   Cmd.v info
     Term.(
-      const Cmd_wat2wasm.cmd $ profiling $ debug $ unsafe $ optimize
-      $ outfile "wat" $ sourcefile "wat" )
+      const Cmd_wat2wasm.cmd $ profiling $ debug $ unsafe $ optimize $ outfile
+      $ sourcefile )
 
 let cli =
   let open Cmdliner in
diff --git a/src/cmd/cmd_opt.ml b/src/cmd/cmd_opt.ml
index 42fe99fa..95ff24af 100644
--- a/src/cmd/cmd_opt.ml
+++ b/src/cmd/cmd_opt.ml
@@ -8,7 +8,7 @@ let optimize_file ~unsafe filename =
   Compile.File.until_optimize ~unsafe ~optimize:true filename
 
 let print_or_emit ~unsafe file outfile =
-  let+ m = optimize_file ~unsafe file in
+  let* m = optimize_file ~unsafe file in
   let m = Binary_to_text.modul m in
   match outfile with
   | Some name -> Bos.OS.File.writef name "%a@\n" Text.pp_modul m
@@ -16,4 +16,4 @@ let print_or_emit ~unsafe file outfile =
 
 let cmd debug unsafe file outfile =
   if debug then Log.debug_on := true;
-  Result.bind (print_or_emit ~unsafe file outfile) (fun _ -> Ok ())
+  print_or_emit ~unsafe file outfile
diff --git a/test/opt/output.t b/test/opt/output.t
new file mode 100644
index 00000000..f99c975c
--- /dev/null
+++ b/test/opt/output.t
@@ -0,0 +1,10 @@
+  $ owi opt fbinop.wat -o bar.wat
+  $ owi fmt bar.wat
+  (module
+    
+    (type (sub final  (func)))
+    (func $start
+      
+    )
+    (start 0)
+  )
diff --git a/test/wasm2wat/output.t b/test/wasm2wat/output.t
new file mode 100644
index 00000000..ad270c4f
--- /dev/null
+++ b/test/wasm2wat/output.t
@@ -0,0 +1,20 @@
+  $ owi wasm2wat done.wasm -o bar.wat
+  $ owi fmt bar.wat
+  (module
+    
+    (type (sub final  (func (param i32) (param i32) (result i32))))
+    
+    (type (sub final  (func)))
+    (func (param i32) (param i32) (result i32)
+      local.get 0
+      local.get 1
+      i32.add
+    )
+    (func
+      i32.const 22
+      i32.const 20
+      call 0
+      drop
+    )
+    (start 1)
+  )
diff --git a/test/wat2wasm/output.t b/test/wat2wasm/output.t
new file mode 100644
index 00000000..2cff8873
--- /dev/null
+++ b/test/wat2wasm/output.t
@@ -0,0 +1,26 @@
+  $ owi wat2wasm func.wat -o bar.wasm
+  $ owi run bar.wasm --debug
+  typechecking ...
+  linking      ...
+  interpreting ...
+  stack        : [  ]
+  running instr: call 1
+  calling func : func anonymous
+  stack        : [  ]
+  running instr: f32.const 40.400_001_525_878_906
+  stack        : [ f32.const 40.400_001_525_878_906 ]
+  running instr: call 0
+  calling func : func anonymous
+  stack        : [  ]
+  running instr: f32.const 2.019_999_980_926_513_7
+  stack        : [ f32.const 2.019_999_980_926_513_7 ]
+  running instr: local.tee 1
+  stack        : [ f32.const 2.019_999_980_926_513_7 ]
+  running instr: local.get 0
+  stack        : [ f32.const 40.400_001_525_878_906 ; f32.const 2.019_999_980_926_513_7 ]
+  running instr: f32.add
+  stack        : [ f32.const 42.420_001_983_642_578 ]
+  stack        : [ f32.const 42.420_001_983_642_578 ]
+  running instr: drop
+  stack        : [  ]
+  stack        : [  ]