diff --git a/_pytest/mark.py b/_pytest/mark.py
index 4e304650a..6b66b1876 100644
--- a/_pytest/mark.py
+++ b/_pytest/mark.py
@@ -206,6 +206,24 @@ class MarkDecorator:
         @mark2
         def test_function():
             pass
+
+    When a MarkDecorator instance is called it does the following:
+      1. If called with a single class as its only positional argument and no
+         additional keyword arguments, it attaches itself to the class so it
+         gets applied automatically to all test cases found in that class.
+      2. If called with a single function as its only positional argument and
+         no additional keyword arguments, it attaches a MarkInfo object to the
+         function, containing all the arguments already stored internally in
+         the MarkDecorator.
+      3. When called in any other case, it performs a 'fake construction' call,
+         i.e. it returns a new MarkDecorator instance with the original
+         MarkDecorator's content updated with the arguments passed to this
+         call.
+
+    Note: The rules above prevent MarkDecorator objects from storing only a
+    single function or class reference as their positional argument with no
+    additional keyword or positional arguments.
+
     """
     def __init__(self, name, args=None, kwargs=None):
         self.name = name
@@ -224,7 +242,7 @@ class MarkDecorator:
     def __call__(self, *args, **kwargs):
         """ if passed a single callable argument: decorate it with mark info.
             otherwise add *args/**kwargs in-place to mark information. """
-        if args:
+        if args and not kwargs:
             func = args[0]
             if len(args) == 1 and (istestfunc(func) or
                                    hasattr(func, '__bases__')):
diff --git a/testing/test_mark.py b/testing/test_mark.py
index ba4c427fe..ce2e4b60d 100644
--- a/testing/test_mark.py
+++ b/testing/test_mark.py
@@ -57,6 +57,17 @@ class TestMark:
         assert f.world.args[0] == "hello"
         mark.world("world")(f)
 
+    def test_pytest_mark_positional_func_and_keyword(self):
+        mark = Mark()
+        def f():
+            raise Exception
+        m = mark.world(f, omega="hello")
+        def g():
+            pass
+        assert m(g) == g
+        assert g.world.args[0] is f
+        assert g.world.kwargs["omega"] == "hello"
+
     def test_pytest_mark_reuse(self):
         mark = Mark()
         def f():