diff --git a/ftdetect/sum.vim b/ftdetect/sum.vim
new file mode 100644
index 0000000..3ee9307
--- /dev/null
+++ b/ftdetect/sum.vim
@@ -0,0 +1 @@
+autocmd BufRead,BufNewFile *.sum set filetype=gosum
diff --git a/lua/go/gopls.lua b/lua/go/gopls.lua
index 950808d..bc58837 100644
--- a/lua/go/gopls.lua
+++ b/lua/go/gopls.lua
@@ -170,7 +170,7 @@ local setups = {
       },
     },
   },
-  filetypes = { "go", "gomod", "gohtmltmpl", "gotexttmpl" },
+  filetypes = { "go", "gomod", "gosum", "gotmpl", "gohtmltmpl", "gotexttmpl" },
   message_level = vim.lsp.protocol.MessageType.Error,
   cmd = {
     "gopls", -- share the gopls instance if there is one already