diff --git a/autoload/committia.vim b/autoload/committia.vim
index 38ccb4c..23f0290 100644
--- a/autoload/committia.vim
+++ b/autoload/committia.vim
@@ -31,6 +31,7 @@ function! s:open_window(vcs, type, info, ft) abort
     execute 'silent' g:committia_{coltype}{a:type}_window_opencmd bufname
     let a:info[a:type . '_winnr'] = bufwinnr(bufname)
     let a:info[a:type . '_bufnr'] = bufnr('%')
+    setlocal modifiable
     call append(0, content)
     execute 0
     execute 'setlocal ft=' . a:ft