diff --git a/spec/util_async_spec.lua b/spec/util_async_spec.lua
index 7c1696b5b..959ad65b5 100644
--- a/spec/util_async_spec.lua
+++ b/spec/util_async_spec.lua
@@ -601,6 +601,7 @@ describe("util.async", function()
 			end);
 			async.once(f);
 			assert.spy(f).was.called();
+			assert.spy(f).was.called_with();
 		end);
 		it("should propagate errors", function ()
 			local function should_error()
diff --git a/util/async.lua b/util/async.lua
index e8469e511..f042b1772 100644
--- a/util/async.lua
+++ b/util/async.lua
@@ -231,7 +231,7 @@ do
 	};
 	local function once_runner(func) func(); end
 	function once(func)
-		local r = runner(func, once_watchers);
+		local r = runner(once_runner, once_watchers);
 		return r:run(func);
 	end
 end