diff --git a/src/nvim/terminal.c b/src/nvim/terminal.c
index e8ee47986d..e879e695dc 100644
--- a/src/nvim/terminal.c
+++ b/src/nvim/terminal.c
@@ -580,7 +580,9 @@ void terminal_open(Terminal **termpp, buf_T *buf)
     assert(term->invalid_start >= 0);
   }
   refresh_screen(term, buf);
+  buf->b_locked++;
   set_option_value(kOptBuftype, STATIC_CSTR_AS_OPTVAL("terminal"), OPT_LOCAL);
+  buf->b_locked--;
 
   if (buf->b_ffname != NULL) {
     buf_set_term_title(buf, buf->b_ffname, strlen(buf->b_ffname));
diff --git a/test/functional/terminal/buffer_spec.lua b/test/functional/terminal/buffer_spec.lua
index d31cee89dd..6eb43e10ba 100644
--- a/test/functional/terminal/buffer_spec.lua
+++ b/test/functional/terminal/buffer_spec.lua
@@ -1165,8 +1165,13 @@ describe(':terminal buffer', function()
     eq({ mode = 'nt', blocking = false }, api.nvim_get_mode())
   end)
 
-  it('does not allow b:term_title watcher to delete buffer', function()
+  it('does not allow OptionSet or b:term_title watcher to delete buffer', function()
+    local au = api.nvim_create_autocmd('OptionSet', { command = 'bwipeout!' })
     local chan = api.nvim_open_term(0, {})
+    matches('^E937: ', api.nvim_get_vvar('errmsg'))
+    api.nvim_del_autocmd(au)
+    api.nvim_set_vvar('errmsg', '')
+
     api.nvim_chan_send(chan, '\027]2;SOME_TITLE\007')
     eq('SOME_TITLE', api.nvim_buf_get_var(0, 'term_title'))
     command([[call dictwatcheradd(b:, 'term_title', {-> execute('bwipe!')})]])