diff --git a/.config/nvim/after/ftplugin/elixir.lua b/.config/nvim/after/ftplugin/elixir.lua
new file mode 100644
--- /dev/null
+++ b/.config/nvim/after/ftplugin/elixir.lua
@@ -0,0 +1,57 @@
+-- elixir-tools installs elixir-ls in directories by version and otp version in
+-- order to match up the right version with your app.  it doesn't expose what
+-- path is in use except for how it launches elixir-ls, so we can scrape it out
+-- of there.  it's not clear to me how nvim-dap would handle an adapter's
+-- definition changing, so i wouldn't expect this to work well with more than
+-- one version in the same nvim session.
+
+local function find_elixir_lsp_dap_cmd(bufnr)
+  local elixir_lsp = vim.lsp.get_active_clients({
+    idname = "ElixirLS",
+    bufnr = bufnr or vim.api.nvim_get_current_buf(),
+  })[1]
+
+  if elixir_lsp then
+    local elixir_lsp_cmd = elixir_lsp.config.cmd[1]
+    local dap_cmd = elixir_lsp_cmd:gsub("language_server.", "debug_adapter.")
+
+    return dap_cmd
+  end
+end
+
+local dap = require("dap")
+
+dap.adapters.mix_task = function(callback, _)
+  local dap_cmd = find_elixir_lsp_dap_cmd()
+
+  if dap_cmd then
+    callback({
+      type = 'executable',
+      command = find_elixir_lsp_dap_cmd(),
+      args = {},
+    })
+  end
+end
+
+dap.configurations.elixir = {
+  {
+    type = "mix_task",
+    name = "mix test",
+    task = 'test',
+    taskArgs = { "--trace" },
+    request = "launch",
+    startApps = true,
+    projectDir = "${workspaceFolder}",
+    requireFiles = {
+      "test/**/test_helper.exs",
+      "test/**/*_test.exs"
+    }
+  },
+  {
+    type = "mix_task",
+    name = "phx.server",
+    request = "launch",
+    task = "phx.server",
+    projectDir = "${workspaceFolder}"
+  },
+}