diff --git a/README.md b/README.md
index a3aa740..dbeb900 100644
--- a/README.md
+++ b/README.md
@@ -121,11 +121,12 @@ behavior with `g:fzf_preview_window`. Here are some examples:
 "   - CTRL-/ will toggle preview window.
 " - Note that this array is passed as arguments to fzf#vim#with_preview function.
 " - To learn more about preview window options, see `--preview-window` section of `man fzf`.
-let g:fzf_preview_window = ['right:50%', 'ctrl-/']
+let g:fzf_preview_window = ['right,50%', 'ctrl-/']
 
-" Preview window on the upper side of the window with 40% height,
-" hidden by default, ctrl-/ to toggle
-let g:fzf_preview_window = ['up:40%:hidden', 'ctrl-/']
+" Preview window is hidden by default. You can toggle it with ctrl-/.
+" It will show on the right with 50% width, but if the width is smaller
+" than 70 columns, it will show above the candidate list
+let g:fzf_preview_window = ['hidden,right,50%,<70(up,40%)', 'ctrl-/']
 
 " Empty value to disable preview window altogether
 let g:fzf_preview_window = []
diff --git a/doc/fzf-vim.txt b/doc/fzf-vim.txt
index a04a17b..188abd0 100644
--- a/doc/fzf-vim.txt
+++ b/doc/fzf-vim.txt
@@ -186,11 +186,12 @@ behavior with `g:fzf_preview_window`. Here are some examples:
     "   - CTRL-/ will toggle preview window.
     " - Note that this array is passed as arguments to fzf#vim#with_preview function.
     " - To learn more about preview window options, see `--preview-window` section of `man fzf`.
-    let g:fzf_preview_window = ['right:50%', 'ctrl-/']
+    let g:fzf_preview_window = ['right,50%', 'ctrl-/']
 
-    " Preview window on the upper side of the window with 40% height,
-    " hidden by default, ctrl-/ to toggle
-    let g:fzf_preview_window = ['up:40%:hidden', 'ctrl-/']
+    " Preview window is hidden by default. You can toggle it with ctrl-/.
+    " It will show on the right with 50% width, but if the width is smaller
+    " than 70 columns, it will show above the candidate list
+    let g:fzf_preview_window = ['hidden,right,50%,<70(up,40%)', 'ctrl-/']
 
     " Empty value to disable preview window altogether
     let g:fzf_preview_window = []