diff --git a/emitter.tl-dev-1.rockspec b/emitter.tl-dev-1.rockspec
index 963d561..8bcc6d3 100644
--- a/emitter.tl-dev-1.rockspec
+++ b/emitter.tl-dev-1.rockspec
@@ -26,6 +26,7 @@ dependencies = {
 }
 test_dependencies = {
   "busted",
+  "busted-tl",
 }
 build_dependencies = {
   "tl >= 0.24.1",
@@ -34,6 +35,9 @@ build_dependencies = {
 }
 test = {
   type = "busted",
+  flags = {
+    "--loaders=teal",
+  },
 }
 build = {
   type = "builtin",
diff --git a/spec/emitter_spec.lua b/spec/emitter_spec.tl
similarity index 55%
rename from spec/emitter_spec.lua
rename to spec/emitter_spec.tl
index 7e3f98d..8db9a56 100644
--- a/spec/emitter_spec.lua
+++ b/spec/emitter_spec.tl
@@ -1,12 +1,21 @@
+global describe: function(string, function)
+global it: function(string, function)
+
 local Emitter = require("emitter")
 
-local Greet = {}
-function Greet.new(name)
+local record Greet is Emitter.Event
+  name: string
+end
+
+function Greet.new(name: string): Greet
   return { type = Greet, name = name }
 end
 
-local Depart = {}
-function Depart.new(name)
+local record Depart is Emitter.Event
+    name: string
+end
+
+function Depart.new(name: string): Depart
   return { type = Depart, name = name }
 end
 
@@ -19,150 +28,151 @@ describe("Emitter", function()
 
   describe("subscribe", function()
     it("emits in order", function()
-      local messages = {}
+      local messages: {string} = {}
       local emitter = Emitter.new()
-      emitter:on(Greet, function(greet)
+      emitter:on(Greet, function(greet: Greet)
         table.insert(messages, greet.name .. " 1")
       end)
-      emitter:on(Greet, function(greet)
+      emitter:on(Greet, function(greet: Greet)
         table.insert(messages, greet.name .. " 2")
       end)
-      emitter:on(Depart, function(depart)
+      emitter:on(Depart, function(depart: Depart)
         table.insert(messages, "Depart: " .. depart.name)
       end)
       emitter:emit(Greet.new("Hi"))
-      assert.equals(2, #messages)
-      assert.equals("Hi 1", messages[1])
-      assert.equals("Hi 2", messages[2])
+      assert(2 == #messages)
+      assert("Hi 1" == messages[1])
+      assert("Hi 2" == messages[2])
 
       emitter:emit(Depart.new("Bye"))
-      assert.equals(3, #messages)
-      assert.equals("Depart: Bye", messages[3])
+      assert(3 == #messages)
+      assert("Depart: Bye" == messages[3])
     end)
 
     it("can prepend events", function()
-      local messages = {}
+      local messages: {string} = {}
       local emitter = Emitter.new()
-      emitter:on(Greet, function(greet)
+      emitter:on(Greet, function(greet: Greet)
         table.insert(messages, greet.name .. " 1")
       end, { position = "first" })
-      emitter:on(Greet, function(greet)
+      emitter:on(Greet, function(greet: Greet)
         table.insert(messages, greet.name .. " 2")
       end, { position = "first" })
       emitter:emit(Greet.new("Hi"))
-      assert.equals(2, #messages)
-      assert.equals("Hi 2", messages[1])
-      assert.equals("Hi 1", messages[2])
+      assert(2 == #messages)
+      assert("Hi 2" == messages[1])
+      assert("Hi 1" == messages[2])
     end)
   end)
 
   describe("unsubscribe", function()
     it("emits once", function()
-      local messages = {}
+      local messages: {string} = {}
       local emitter = Emitter.new()
-      emitter:once(Greet, function(greet)
+      emitter:once(Greet, function(greet: Greet)
         table.insert(messages, greet.name .. " 1")
       end)
-      emitter:once(Greet, function(greet)
+      emitter:once(Greet, function(greet: Greet)
         table.insert(messages, greet.name .. " 2")
       end)
 
       emitter:emit(Greet.new("Hi"))
-      assert.equals(2, #messages)
-      assert.equals("Hi 1", messages[1])
-      assert.equals("Hi 2", messages[2])
+      assert(2 == #messages)
+      assert("Hi 1" == messages[1])
+      assert("Hi 2" == messages[2])
 
       emitter:emit(Greet.new("Hi"))
-      assert.equals(2, #messages)
+      assert(2 == #messages)
     end)
 
     it("can unsubscribe by receiver", function()
-      local messages = {}
+      local messages: {string} = {}
       local emitter = Emitter.new()
-      local listener = function(greet)
+      local listener = function(greet: Greet)
         table.insert(messages, greet.name)
       end
       emitter:on(Greet, listener)
       emitter:emit(Greet.new("Hi"))
-      assert.equals(1, #messages)
-      assert.equals("Hi", messages[1])
+      assert(1 == #messages)
+      assert("Hi" == messages[1])
 
       emitter:off(Greet, listener)
       emitter:emit(Greet.new("Hi"))
-      assert.equals(1, #messages)
+      assert(1 == #messages)
     end)
 
     it("can unsubscribe by id", function()
-      local messages = {}
+      local messages: {string} = {}
       local emitter = Emitter.new()
-      local listener = function(greet)
+      local listener = function(greet: Greet)
         table.insert(messages, greet.name)
       end
       emitter:on(Greet, listener, { id = "id" })
       emitter:emit(Greet.new("Hi"))
-      assert.equals(1, #messages)
-      assert.equals("Hi", messages[1])
+      assert(1 == #messages)
+      assert("Hi" == messages[1])
 
       emitter:off(Greet, "id")
       emitter:emit(Greet.new("Hi"))
-      assert.equals(1, #messages)
+      assert(1 == #messages)
     end)
 
     it("can unsubscribe multiple by id", function()
-      local messages = {}
+      local messages: {string} = {}
       local emitter = Emitter.new()
-      local listener = function(greet)
+      local listener = function(greet: Greet)
         table.insert(messages, greet.name)
       end
       emitter:on(Greet, listener, { id = "id" })
       emitter:on(Greet, listener, { id = "id" })
       emitter:emit(Greet.new("Hi"))
 
-      assert.equals(2, #messages)
-      assert.equals("Hi", messages[1])
-      assert.equals("Hi", messages[2])
+      assert(2 == #messages)
+      assert("Hi" == messages[1])
+      assert("Hi" == messages[2])
 
       emitter:off(Greet, "id")
       emitter:emit(Greet.new("Hi"))
-      assert.equals(2, #messages)
+      assert(2 == #messages)
     end)
   end)
 
   describe("forwards events", function()
     it("forwards events to an emitter", function()
-      local messages = {}
-      local forwarded = {}
+      local messages: {string} = {}
+      local forwarded: {string} = {}
 
       local emitter = Emitter.new()
       local forward = Emitter.new()
 
-      emitter:on(Greet, function(greet)
+      emitter:on(Greet, function(greet: Greet)
         table.insert(messages, greet.name)
       end)
 
-      forward:on(Greet, function(greet)
+      forward:on(Greet, function(greet: Greet)
         table.insert(forwarded, greet.name)
       end)
 
       emitter:startForwarding(forward)
       emitter:emit(Greet.new("Hi"))
 
-      assert.equals(1, #messages)
-      assert.equals("Hi", messages[1])
-      assert.equals(1, #forwarded)
-      assert.equals("Hi", forwarded[1])
+      assert(1 == #messages)
+      assert("Hi" == messages[1])
+      assert(1 == #forwarded)
+      assert("Hi" == forwarded[1])
 
       forward:emit(Greet.new("Hi"))
 
-      assert.equals(1, #messages)
-      assert.equals(2, #forwarded)
+      assert(1 == #messages)
+      assert(2 == #forwarded)
 
       emitter:stopForwarding(forward)
       emitter:emit(Greet.new("Hello"))
 
-      assert.equals(2, #messages)
-      assert.equals("Hello", messages[2])
-      assert.equals(2, #forwarded)
+      assert(2 == #messages)
+      assert("Hello" == messages[2])
+      assert(2 == #forwarded)
     end)
   end)
 end)
+