diff --git a/ftplugin/erlang.lua b/ftplugin/erlang.lua
new file mode 100644
index 0000000..550d766
--- /dev/null
+++ b/ftplugin/erlang.lua
@@ -0,0 +1,4 @@
+local map = require('utils').create_buf_map(0)
+
+-- easy insertion of trailing . from insert mode.
+map('i', '..', '<Esc>A.<Esc>')
diff --git a/lua/editor.lua b/lua/editor.lua
index 450160b..0af16f8 100644
--- a/lua/editor.lua
+++ b/lua/editor.lua
@@ -79,3 +79,17 @@ opt.updatetime = 100
 
 -- theme
 opt.termguicolors = true
+
+-- filetypes
+vim.filetype.add({
+  extension = {
+    vert = 'glsl',
+    frag = 'glsl',
+    xrl = 'erlang',
+    yrl = 'erlang',
+    src = 'erlang',
+  },
+  filename = {
+    ['rebar.config'] = 'erlang',
+  },
+})
diff --git a/lua/plugins/treesitter.lua b/lua/plugins/treesitter.lua
index b89c4e8..7a6e390 100644
--- a/lua/plugins/treesitter.lua
+++ b/lua/plugins/treesitter.lua
@@ -2,6 +2,8 @@ local config = {
   ensure_installed = {
     'rust',
     'css',
+    'erlang',
+    'elixir',
     'html',
     'javascript',
     'jsdoc',