diff --git a/lua/CopilotChat/config/mappings.lua b/lua/CopilotChat/config/mappings.lua
index baf2f82c..2f64710e 100644
--- a/lua/CopilotChat/config/mappings.lua
+++ b/lua/CopilotChat/config/mappings.lua
@@ -349,6 +349,8 @@ return {
       if copilot.config.mappings.show_diff.full_diff then
         local modified = utils.buf_valid(diff.bufnr) and vim.api.nvim_buf_get_lines(diff.bufnr, 0, -1, false) or {}
 
+        opts.syntax = diff.filetype
+
         -- Apply all diffs from same file
         if #modified > 0 then
           -- Find all diffs from the same file in this section
@@ -376,7 +378,7 @@ return {
             end
             local change_lines = vim.split(file_diff.change, '\n')
             for i, line in ipairs(change_lines) do
-              table.insert(modified, start_idx + i, line)
+              table.insert(modified, start_idx + i - 1, line)
             end
           end
 
@@ -400,6 +402,10 @@ return {
         end
 
         opts.on_hide = function()
+          vim.api.nvim_win_call(vim.fn.bufwinid(diff.bufnr), function()
+            vim.cmd('diffoff')
+          end)
+
           vim.api.nvim_win_call(copilot.chat.winnr, function()
             vim.cmd('diffoff')
           end)
diff --git a/lua/CopilotChat/ui/overlay.lua b/lua/CopilotChat/ui/overlay.lua
index 9b70cb5e..e55b867f 100644
--- a/lua/CopilotChat/ui/overlay.lua
+++ b/lua/CopilotChat/ui/overlay.lua
@@ -39,7 +39,6 @@ function Overlay:show(text, winnr, filetype, syntax, on_show, on_hide)
 
   self:validate()
   vim.api.nvim_win_set_hl_ns(winnr, self.hl_ns)
-  text = text .. '\n'
 
   self.cursor = vim.api.nvim_win_get_cursor(winnr)
   vim.api.nvim_win_set_buf(winnr, self.bufnr)