diff --git a/README-VIM.md b/README-VIM.md
index 6751d25..e727dd1 100644
--- a/README-VIM.md
+++ b/README-VIM.md
@@ -294,7 +294,7 @@ The following table summarizes the available options.
 | `options`                  | string/list   | Options to fzf                                                        |
 | `dir`                      | string        | Working directory                                                     |
 | `up`/`down`/`left`/`right` | number/string | (Layout) Window position and size (e.g. `20`, `50%`)                  |
-| `tmux`                     | string        | (Layout) fzf-tmux options (e.g. `-p90%,60%`)                          |
+| `tmux`                     | string        | (Layout) `--tmux` options (e.g. `90%,70%`)                            |
 | `window` (Vim 8 / Neovim)  | string        | (Layout) Command to open fzf window (e.g. `vertical aboveleft 30new`) |
 | `window` (Vim 8 / Neovim)  | dict          | (Layout) Popup window settings (e.g. `{'width': 0.9, 'height': 0.6}`) |
 
@@ -457,12 +457,13 @@ let g:fzf_layout = { 'window': { 'width': 0.9, 'height': 0.6 } }
 ```
 
 Alternatively, you can make fzf open in a tmux popup window (requires tmux 3.2
-or above) by putting fzf-tmux options in `tmux` key.
+or above) by putting `--tmux` option value in `tmux` key.
 
 ```vim
-" See `man fzf-tmux` for available options
+" See `--tmux` option in `man fzf` for available options
+" [center|top|bottom|left|right][,SIZE[%]][,SIZE[%]]
 if exists('$TMUX')
-  let g:fzf_layout = { 'tmux': '-p90%,60%' }
+  let g:fzf_layout = { 'tmux': '90%,70%' }
 else
   let g:fzf_layout = { 'window': { 'width': 0.9, 'height': 0.6 } }
 endif
diff --git a/doc/fzf.txt b/doc/fzf.txt
index cf8c6af..f946184 100644
--- a/doc/fzf.txt
+++ b/doc/fzf.txt
@@ -311,7 +311,7 @@ The following table summarizes the available options.
   `options`                   | string/list   | Options to fzf
   `dir`                       | string        | Working directory
   `up` / `down` / `left` / `right`  | number/string | (Layout) Window position and size (e.g.  `20` ,  `50%` )
-  `tmux`                      | string        | (Layout) fzf-tmux options (e.g.  `-p90%,60%` )
+  `tmux`                      | string        | (Layout) `--tmux` options (e.g.  `90%,70%` )
   `window`  (Vim 8 / Neovim)  | string        | (Layout) Command to open fzf window (e.g.  `vertical aboveleft 30new` )
   `window`  (Vim 8 / Neovim)  | dict          | (Layout) Popup window settings (e.g.  `{'width': 0.9, 'height': 0.6}` )
  ---------------------------+---------------+----------------------------------------------------------------------
@@ -469,11 +469,12 @@ in Neovim.
     let g:fzf_layout = { 'window': { 'width': 0.9, 'height': 0.6 } }
 <
 Alternatively, you can make fzf open in a tmux popup window (requires tmux 3.2
-or above) by putting fzf-tmux options in `tmux` key.
+or above) by putting `--tmux` options in `tmux` key.
 >
-    " See `man fzf-tmux` for available options
+    " See `--tmux` option in `man fzf` for available options
+    " [center|top|bottom|left|right][,SIZE[%]][,SIZE[%]]
     if exists('$TMUX')
-      let g:fzf_layout = { 'tmux': '-p90%,60%' }
+      let g:fzf_layout = { 'tmux': '90%,70%' }
     else
       let g:fzf_layout = { 'window': { 'width': 0.9, 'height': 0.6 } }
     endif
diff --git a/plugin/fzf.vim b/plugin/fzf.vim
index 51ed138..eee5e9c 100644
--- a/plugin/fzf.vim
+++ b/plugin/fzf.vim
@@ -573,19 +573,21 @@ function! s:fzf_tmux(dict)
   if empty(size)
     for o in ['up', 'down', 'left', 'right']
       if s:present(a:dict, o)
-        let spec = a:dict[o]
-        if (o == 'up' || o == 'down') && spec[0] == '~'
-          let size = '-'.o[0].s:calc_size(&lines, spec, a:dict)
-        else
-          " Legacy boolean option
-          let size = '-'.o[0].(spec == 1 ? '' : substitute(spec, '^\~', '', ''))
-        endif
+        let size = o . ',' . a:dict[o]
         break
       endif
     endfor
   endif
-  return printf('LINES=%d COLUMNS=%d %s %s %s --',
-    \ &lines, &columns, fzf#shellescape(s:fzf_tmux), size, (has_key(a:dict, 'source') ? '' : '-'))
+
+  " Legacy fzf-tmux options
+  if size =~ '-'
+    return printf('LINES=%d COLUMNS=%d %s %s %s --',
+          \ &lines, &columns, fzf#shellescape(s:fzf_tmux), size, (has_key(a:dict, 'source') ? '' : '-'))
+  end
+
+  " Using native --tmux option
+  let in = (has_key(a:dict, 'source') ? '' : ' < /dev/tty')
+  return printf('%s --tmux %s%s', fzf#shellescape(fzf#exec()), size, in)
 endfunction
 
 function! s:splittable(dict)