diff --git a/tests/test-types.lua b/tests/test-types.lua
index df2566c0..7cf313de 100644
--- a/tests/test-types.lua
+++ b/tests/test-types.lua
@@ -35,11 +35,16 @@ asserteq(types.is_callable(List),true)
 do
     local mt = setmetatable({}, {
         __index = {
-            __call = function() end
+            __call = function() return "ok" end
         }
     })
     asserteq(type(mt.__call), "function") -- __call is looked-up through another metatable
     local nc = setmetatable({}, mt)
+    -- proof-of-pudding, let's call it. To verify Lua behaves the same on all engines
+    local success, result = pcall(function() return nc() end)
+    assert(result ~= "ok", "expected result to not be 'ok'")
+    asserteq(success, false)
+    -- real test now
     asserteq(types.is_callable(nc), false) -- NOT callable, since __call is fetched using RAWget by Lua
 end