diff --git a/clients/vim/autoload/tabby/keybindings.vim b/clients/vim/autoload/tabby/keybindings.vim
index 6922603..4fea4d2 100644
--- a/clients/vim/autoload/tabby/keybindings.vim
+++ b/clients/vim/autoload/tabby/keybindings.vim
@@ -12,11 +12,16 @@ function! tabby#keybindings#Map()
     if !empty(mapcheck('<Tab>', 'i'))
       " fallback to the original <Tab> mapping
       let tab_maparg = maparg('<Tab>', 'i', 0, 1)
-      " warp as function if rhs is expr, otherwise encode rhs as json
-      let fallback_rhs = tab_maparg.expr ? '{ -> ' . tab_maparg.rhs . ' }' : substitute(json_encode(tab_maparg.rhs), '<', '\\<', 'g')
-      " inject <SID>
-      let fallback_rhs = substitute(fallback_rhs, '<SID>', "\<SNR>" . get(tab_maparg, 'sid') . '_', 'g')
-      exec 'imap <script><silent><nowait><expr> <Tab> tabby#Accept(' . fallback_rhs . ')'
+      if toupper(tab_maparg.rhs) == '<NOP>'
+        " if the original <Tab> mapping is <nop>, no need to fallback
+        imap <script><silent><nowait><expr> <Tab> tabby#Accept()
+      else
+        " warp as function if rhs is expr, otherwise encode rhs as json
+        let fallback_rhs = tab_maparg.expr ? '{ -> ' . tab_maparg.rhs . ' }' : substitute(json_encode(tab_maparg.rhs), '<', '\\<', 'g')
+        " inject <SID>
+        let fallback_rhs = substitute(fallback_rhs, '<SID>', "\<SNR>" . get(tab_maparg, 'sid') . '_', 'g')
+        exec 'imap ' . (get(tab_maparg, 'script') ? '<script>' : '') . '<silent><nowait><expr> <Tab> tabby#Accept(' . fallback_rhs . ')'
+      endif
     else
       " fallback to input \t
       imap <script><silent><nowait><expr> <Tab> tabby#Accept("\t")