diff --git a/py/test/funcargs.py b/py/test/funcargs.py
index 22ba09807..f1c5d2708 100644
--- a/py/test/funcargs.py
+++ b/py/test/funcargs.py
@@ -33,9 +33,11 @@ class Metafunc:
         self._calls = []
         self._ids = py.builtin.set()
 
-    def addcall(self, funcargs=None, id=None, param=_notexists):
+    def addcall(self, funcargs=None, id=_notexists, param=_notexists):
         assert funcargs is None or isinstance(funcargs, dict)
         if id is None:
+            raise ValueError("id=None not allowed") 
+        if id is _notexists:
             id = len(self._calls)
         id = str(id)
         if id in self._ids:
diff --git a/py/test/pycollect.py b/py/test/pycollect.py
index 620d39a7d..16fd5d5d3 100644
--- a/py/test/pycollect.py
+++ b/py/test/pycollect.py
@@ -313,6 +313,7 @@ class Function(FunctionMixin, py.test.collect.Item):
     """ a Function Item is responsible for setting up  
         and executing a Python callable test object.
     """
+    _genid = None
     def __init__(self, name, parent=None, config=None, args=(), 
                  callspec=None, callobj=_dummy):
         super(Function, self).__init__(name, parent, config=config) 
@@ -320,9 +321,13 @@ class Function(FunctionMixin, py.test.collect.Item):
         if args:
             assert not callspec, "yielded functions (deprecated) cannot have funcargs" 
         else:
-            self.funcargs = callspec and callspec.funcargs or {}
-            if hasattr(callspec, "param"):
-                self._requestparam = callspec.param
+            if callspec is not None:
+                self.funcargs = callspec.funcargs or {}
+                self._genid = callspec.id 
+                if hasattr(callspec, "param"):
+                    self._requestparam = callspec.param
+            else:
+                self.funcargs = {}
         if callobj is not _dummy: 
             self._obj = callobj 
 
@@ -351,8 +356,8 @@ class Function(FunctionMixin, py.test.collect.Item):
                     self._args == other._args and
                     self.parent == other.parent and
                     self.obj == other.obj and 
-                    getattr(self, '_requestparam', None) == 
-                    getattr(other, '_requestparam', None) 
+                    getattr(self, '_genid', None) == 
+                    getattr(other, '_genid', None) 
             )
         except AttributeError:
             pass
diff --git a/py/test/testing/test_funcargs.py b/py/test/testing/test_funcargs.py
index bb7e832ae..b34a2e662 100644
--- a/py/test/testing/test_funcargs.py
+++ b/py/test/testing/test_funcargs.py
@@ -298,6 +298,8 @@ class TestMetafunc:
     def test_addcall_id(self):
         def func(arg1): pass
         metafunc = funcargs.Metafunc(func)
+        py.test.raises(ValueError, "metafunc.addcall(id=None)")
+
         metafunc.addcall(id=1)
         py.test.raises(ValueError, "metafunc.addcall(id=1)")
         py.test.raises(ValueError, "metafunc.addcall(id='1')")
@@ -338,6 +340,7 @@ class TestGenfuncFunctional:
                 metafunc.addcall(param=metafunc) 
 
             def pytest_funcarg__metafunc(request):
+                assert request._pyfuncitem._genid == "0"
                 return request.param 
 
             def test_function(metafunc):
diff --git a/py/test/testing/test_pycollect.py b/py/test/testing/test_pycollect.py
index 10efc9e55..402ace27a 100644
--- a/py/test/testing/test_pycollect.py
+++ b/py/test/testing/test_pycollect.py
@@ -242,25 +242,16 @@ class TestFunction:
         assert f1 == f1_b
         assert not f1 != f1_b
 
+    def test_function_equality_with_callspec(self, tmpdir):
+        config = py.test.config._reparse([tmpdir])
         class callspec1:
             param = 1
             funcargs = {}
+            id = "hello"
         class callspec2:
-            param = 2
-            funcargs = {}
-        f5 = py.test.collect.Function(name="name", config=config, 
-                                      callspec=callspec1, callobj=isinstance)
-        f5b = py.test.collect.Function(name="name", config=config, 
-                                      callspec=callspec2, callobj=isinstance)
-        assert f5 != f5b
-        assert not (f5 == f5b)
-
-        class callspec1:
             param = 1
             funcargs = {}
-        class callspec2:
-            param = 2
-            funcargs = {}
+            id = "world"
         f5 = py.test.collect.Function(name="name", config=config, 
                                       callspec=callspec1, callobj=isinstance)
         f5b = py.test.collect.Function(name="name", config=config,