diff --git a/clients/vim/autoload/tabby/keybindings.vim b/clients/vim/autoload/tabby/keybindings.vim
index 7042c04..6922603 100644
--- a/clients/vim/autoload/tabby/keybindings.vim
+++ b/clients/vim/autoload/tabby/keybindings.vim
@@ -12,8 +12,8 @@ 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
-      let fallback_rhs = tab_maparg.expr ? '{ -> ' . tab_maparg.rhs . ' }' : tab_maparg.rhs
+      " 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 . ')'