diff --git a/src/wrappers.py b/src/wrappers.py
index d1e35c8..2ead039 100644
--- a/src/wrappers.py
+++ b/src/wrappers.py
@@ -513,18 +513,18 @@ try:
 except ImportError:
     pass
 
-def _weak_function_proxy_callback(ref, self, callback):
-    if self._self_expired:
+def _weak_function_proxy_callback(ref, proxy, callback):
+    if proxy._self_expired:
         return
 
-    self._self_expired = True
+    proxy._self_expired = True
 
     # This could raise an exception. We let it propagate back and let
     # the weakref.proxy() deal with it, at which point it generally
     # prints out a short error message direct to stderr and keeps going.
 
     if callback is not None:
-        callback(self)
+        callback(proxy)
 
 class WeakFunctionProxy(ObjectProxy):
 
@@ -542,12 +542,13 @@ class WeakFunctionProxy(ObjectProxy):
         # the callback here so as not to cause any odd reference cycles.
 
         _callback = callback and functools.partial(
-                _weak_function_proxy_callback, self=self, callback=callback)
+                _weak_function_proxy_callback, proxy=self,
+                callback=callback)
 
         self._self_expired = False
 
         try:
-            self._self_instance = weakref.proxy(wrapped.__self__, _callback)
+            self._self_instance = weakref.ref(wrapped.__self__, _callback)
 
             super(WeakFunctionProxy, self).__init__(
                     weakref.proxy(wrapped.__func__, _callback))
@@ -563,7 +564,7 @@ class WeakFunctionProxy(ObjectProxy):
         # function as that will trigger the reference error prior to
         # calling if the reference had expired.
 
-        instance = self._self_instance and self._self_instance
+        instance = self._self_instance and self._self_instance()
         function = self._self_wrapped and self._self_wrapped
 
         # If the wrapped function was originally a bound function, for
diff --git a/tests/test_weak_function_proxy.py b/tests/test_weak_function_proxy.py
new file mode 100644
index 0000000..9535b45
--- /dev/null
+++ b/tests/test_weak_function_proxy.py
@@ -0,0 +1,175 @@
+from __future__ import print_function
+
+import unittest
+import gc
+
+import wrapt
+
+class TestWeakFunctionProxy(unittest.TestCase):
+
+    def test_isinstance(self):
+        def function(a, b):
+            return a, b
+
+        proxy = wrapt.WeakFunctionProxy(function)
+
+        self.assertTrue(isinstance(proxy, type(function)))
+
+    def test_no_callback(self):
+        def function(a, b):
+            return a, b
+
+        proxy = wrapt.WeakFunctionProxy(function)
+
+        self.assertEqual(proxy(1, 2), (1, 2))
+
+        function = None
+        gc.collect()
+
+    def test_call_expired(self):
+        def function(a, b):
+            return a, b
+
+        proxy = wrapt.WeakFunctionProxy(function)
+
+        self.assertEqual(proxy(1, 2), (1, 2))
+
+        function = None
+        gc.collect()
+
+        def run(*args):
+            proxy()
+
+        self.assertRaises(ReferenceError, run, ())
+
+    def test_function(self):
+        def function(a, b):
+            return a, b
+
+        result = []
+
+        def callback(proxy):
+            result.append(id(proxy))
+
+        proxy = wrapt.WeakFunctionProxy(function, callback)
+
+        self.assertEqual(proxy(1, 2), (1, 2))
+
+        function = None
+        gc.collect()
+
+        self.assertEqual(len(result), 1)
+        self.assertEqual(id(proxy), result[0])
+
+    def test_instancemethod_delete_instance(self):
+        class Class(object):
+            def function(self, a, b):
+                return a, b
+
+        result = []
+
+        def callback(proxy):
+            result.append(id(proxy))
+
+        c = Class()
+
+        proxy = wrapt.WeakFunctionProxy(c.function, callback)
+
+        self.assertEqual(proxy(1, 2), (1, 2))
+
+        c = None
+        gc.collect()
+
+        self.assertEqual(len(result), 1)
+        self.assertEqual(id(proxy), result[0])
+
+    def test_instancemethod_delete_function(self):
+        class Class(object):
+            def function(self, a, b):
+                return a, b
+
+        result = []
+
+        def callback(proxy):
+            result.append(id(proxy))
+
+        c = Class()
+
+        proxy = wrapt.WeakFunctionProxy(c.function, callback)
+
+        self.assertEqual(proxy(1, 2), (1, 2))
+
+        del Class.function
+        gc.collect()
+
+        self.assertEqual(len(result), 1)
+        self.assertEqual(id(proxy), result[0])
+
+    def test_instancemethod_delete_function_and_instance(self):
+        class Class(object):
+            def function(self, a, b):
+                return a, b
+
+        result = []
+
+        def callback(proxy):
+            result.append(id(proxy))
+
+        c = Class()
+
+        proxy = wrapt.WeakFunctionProxy(c.function, callback)
+
+        self.assertEqual(proxy(1, 2), (1, 2))
+
+        c = None
+        del Class.function
+        gc.collect()
+
+        self.assertEqual(len(result), 1)
+        self.assertEqual(id(proxy), result[0])
+
+    def test_classmethod(self):
+        class Class(object):
+            @classmethod
+            def function(cls, a, b):
+                self.assertEqual(cls, Class)
+                return a, b
+
+        result = []
+
+        def callback(proxy):
+            result.append(id(proxy))
+
+        proxy = wrapt.WeakFunctionProxy(Class.function, callback)
+
+        self.assertEqual(proxy(1, 2), (1, 2))
+
+        Class = None
+        gc.collect()
+
+        self.assertEqual(len(result), 1)
+        self.assertEqual(id(proxy), result[0])
+
+    def test_staticmethod(self):
+        class Class(object):
+            @staticmethod
+            def function(a, b):
+                return a, b
+
+        result = []
+
+        def callback(proxy):
+            result.append(id(proxy))
+
+        proxy = wrapt.WeakFunctionProxy(Class.function, callback)
+
+        self.assertEqual(proxy(1, 2), (1, 2))
+
+        Class = None
+        gc.collect()
+
+        self.assertEqual(len(result), 1)
+        self.assertEqual(id(proxy), result[0])
+
+if __name__ == '__main__':
+    unittest.main()