diff --git a/README.md b/README.md
index 1dae7bf..8aa8f23 100644
--- a/README.md
+++ b/README.md
@@ -24,7 +24,7 @@ API:
 
 fenster.open(width: integer, height: integer, title: string?, scale: integer?, targetfps: number?): userdata
 
-fenster.sleep(millis: integer)
+fenster.sleep(milliseconds: integer)
 
 fenster.time(): integer
 
diff --git a/spec/fenster_spec.lua b/spec/fenster_spec.lua
index 3aec6a2..b50941f 100644
--- a/spec/fenster_spec.lua
+++ b/spec/fenster_spec.lua
@@ -139,7 +139,7 @@ describe('fenster', function()
 			assert.has_errors(function() fenster.sleep() end)
 		end)
 
-		it('should throw when millis is not an integer', function()
+		it('should throw when milliseconds is not an integer', function()
 			assert.has_errors(function() fenster.sleep('ERROR') end)
 			assert.has_errors(function() fenster.sleep(true) end)
 			assert.has_errors(function() fenster.sleep({}) end)
diff --git a/src/main.c b/src/main.c
index 1a084d6..68363cf 100644
--- a/src/main.c
+++ b/src/main.c
@@ -214,9 +214,9 @@ static int lfenster_open(lua_State *L) {
  * @return Number of return values on the Lua stack
  */
 static int lfenster_sleep(lua_State *L) {
-  const lua_Integer millis = luaL_checkinteger(L, 1);
+  const lua_Integer milliseconds = luaL_checkinteger(L, 1);
 
-  fenster_sleep(millis);
+  fenster_sleep(milliseconds);
 
   return 0;
 }