diff --git a/annotation/typed.py b/annotation/typed.py
index 1c3bb29..577fd11 100644
--- a/annotation/typed.py
+++ b/annotation/typed.py
@@ -455,6 +455,10 @@ def _check_type_constraint(value, constraint):
     else:
         return False
 
+class IncorrectArgument(TypeError):
+  def __str__(self):
+    return '{} expected {!r} actual {!r}'.format(*self.args)
+
 def _check_argument_types(signature, *args, **kwargs):
     """Check that the arguments of a function match the given signature."""
     bound_arguments = signature.bind(*args, **kwargs)
@@ -464,8 +468,11 @@ def _check_argument_types(signature, *args, **kwargs):
         if annotation is EMPTY_ANNOTATION:
             annotation = AnyType
         if not _check_type_constraint(value, annotation):
-            raise TypeError('Incorrect type for "{0}"'.format(name))
+            raise IncorrectArgument(name, annotation, value)
 
+class IncorrectReturnType(TypeError):
+  def __str__(self):
+    return 'expected: {!r} actual: {!r}'.format(*self.args)
 
 def _check_return_type(signature, return_value):
     """Check that the return value of a function matches the signature."""
@@ -473,7 +480,7 @@ def _check_return_type(signature, return_value):
     if annotation is EMPTY_ANNOTATION:
         annotation = AnyType
     if not _check_type_constraint(return_value, annotation):
-        raise TypeError('Incorrect return type')
+        raise IncorrectReturnType(annotation, return_value)
     return return_value
 
 
diff --git a/tests/test_annontations.py b/tests/test_annontations.py
index d1aa269..f9e38a1 100644
--- a/tests/test_annontations.py
+++ b/tests/test_annontations.py
@@ -2,8 +2,7 @@
 from collections import namedtuple
 
 from annotation.typed import (typechecked, Interface, union, AnyType, predicate,
-    optional, typedef, options, only)
-
+    optional, typedef, options, only, IncorrectReturnType, IncorrectArgument)
 
 
 class TypecheckedTest(unittest.TestCase):
@@ -15,8 +14,8 @@ def test(a: int):
             return a
 
         self.assertEqual(1, test(1))
-        self.assertRaises(TypeError, test, 'string')
-        self.assertRaises(TypeError, test, 1.2)
+        self.assertRaises(IncorrectArgument, test, 'string')
+        self.assertRaises(IncorrectArgument, test, 1.2)
 
     def test_single_argument_with_class(self):
 
@@ -29,7 +28,7 @@ def test(a: MyClass):
 
         value = MyClass()
         self.assertEqual(value, test(value))
-        self.assertRaises(TypeError, test, 'string')
+        self.assertRaises(IncorrectArgument, test, 'string')
 
     def test_single_argument_with_subclass(self):
 
@@ -42,7 +41,7 @@ def test(a: MyClass):
 
         value = MySubClass()
         self.assertEqual(value, test(value))
-        self.assertRaises(TypeError, test, 'string')
+        self.assertRaises(IncorrectArgument, test, 'string')
 
     def test_single_argument_with_union_annotation(self):
         from decimal import Decimal
@@ -54,7 +53,7 @@ def test(a: union(int, float, Decimal)):
         self.assertEqual(1, test(1))
         self.assertEqual(1.5, test(1.5))
         self.assertEqual(Decimal('2.5'), test(Decimal('2.5')))
-        self.assertRaises(TypeError, test, 'string')
+        self.assertRaises(IncorrectArgument, test, 'string')
 
     def test_single_argument_with_predicate_annotation(self):
 
@@ -63,7 +62,7 @@ def test(a: predicate(lambda x: x > 0)):
             return a
 
         self.assertEqual(1, test(1))
-        self.assertRaises(TypeError, test, 0)
+        self.assertRaises(IncorrectArgument, test, 0)
 
     def test_single_argument_with_optional_annotation(self):
 
@@ -91,7 +90,7 @@ def f2(a: str, b: str):
             pass
 
         self.assertEqual({}, test(f1))
-        self.assertRaises(TypeError, test, f2)
+        self.assertRaises(IncorrectArgument, test, f2)
 
     def test_single_argument_with_options_annotation(self):
 
@@ -101,7 +100,7 @@ def test(a: options('open', 'write')):
 
         self.assertEqual('open', test('open'))
         self.assertEqual('write', test('write'))
-        self.assertRaises(TypeError, test, 'other')
+        self.assertRaises(IncorrectArgument, test, 'other')
 
     def test_single_argument_with_only_annotation(self):
 
@@ -110,7 +109,7 @@ def test(a: only(int)):
             return a
 
         self.assertEqual(1, test(1))
-        self.assertRaises(TypeError, test, True)
+        self.assertRaises(IncorrectArgument, test, True)
 
     def test_single_argument_with_interface(self):
 
@@ -129,7 +128,7 @@ def test(a: Test):
             return 1
 
         self.assertEqual(1, test(TestImplementation()))
-        self.assertRaises(TypeError, test, Other())
+        self.assertRaises(IncorrectArgument, test, Other())
 
     def test_single_argument_with_no_annotation(self):
 
@@ -148,9 +147,9 @@ def test(a: int, b: str):
             return a, b
 
         self.assertEqual((1, 'string'), test(1, 'string'))
-        self.assertRaises(TypeError, test, 1, 1)
-        self.assertRaises(TypeError, test, 'string', 'string')
-        self.assertRaises(TypeError, test, 'string', 1)
+        self.assertRaises(IncorrectArgument, test, 1, 1)
+        self.assertRaises(IncorrectArgument, test, 'string', 'string')
+        self.assertRaises(IncorrectArgument, test, 'string', 1)
 
     def test_single_argument_with_none_value(self):
 
@@ -158,7 +157,7 @@ def test_single_argument_with_none_value(self):
         def test(a: int):
             return a
 
-        self.assertRaises(TypeError, test, None)
+        self.assertRaises(IncorrectArgument, test, None)
 
     def test_multiple_arguments_some_with_annotations(self):
 
@@ -168,8 +167,8 @@ def test(a, b: str):
 
         self.assertEqual((1, 'string'), test(1, 'string'))
         self.assertEqual(('string', 'string'), test('string', 'string'))
-        self.assertRaises(TypeError, test, 1, 1)
-        self.assertRaises(TypeError, test, 'string', 1)
+        self.assertRaises(IncorrectArgument, test, 1, 1)
+        self.assertRaises(IncorrectArgument, test, 'string', 1)
 
     def test_return_with_builtin_type(self):
 
@@ -178,8 +177,8 @@ def test(a) -> int:
             return a
 
         self.assertEqual(1, test(1))
-        self.assertRaises(TypeError, test, 'string')
-        self.assertRaises(TypeError, test, 1.2)
+        self.assertRaises(IncorrectReturnType, test, 'string')
+        self.assertRaises(IncorrectReturnType, test, 1.2)
 
     def test_return_with_class(self):
 
@@ -195,7 +194,7 @@ def test2() -> MyClass:
             return 1
 
         self.assertIsInstance(test1(), MyClass)
-        self.assertRaises(TypeError, test2)
+        self.assertRaises(IncorrectReturnType, test2)
 
     def test_return_with_sublass(self):
 
@@ -211,7 +210,7 @@ def test2() -> MyClass:
             return 1
 
         self.assertIsInstance(test1(), MyClass)
-        self.assertRaises(TypeError, test2)
+        self.assertRaises(IncorrectReturnType, test2)
 
     def test_return_with_union(self):
 
@@ -221,7 +220,7 @@ def test(a) -> union(int, float):
 
         self.assertEqual(1, test(1))
         self.assertEqual(1.1, test(1.1))
-        self.assertRaises(TypeError, test, 'string')
+        self.assertRaises(IncorrectReturnType, test, 'string')
 
     def test_return_with_interface(self):
 
@@ -244,7 +243,7 @@ def test2() -> Test:
             return 1
 
         self.assertIsInstance(test1(), TestImplementation)
-        self.assertRaises(TypeError, test2)
+        self.assertRaises(IncorrectReturnType, test2)
 
     def test_return_with_none_value(self):
 
@@ -252,7 +251,7 @@ def test_return_with_none_value(self):
         def test(a) -> int:
             return a
 
-        self.assertRaises(TypeError, test, None)
+        self.assertRaises(IncorrectReturnType, test, None)
 
     def test_complex_types(self):
         simple_types = [ 'a', 1, None, 1.1, False ]
@@ -328,12 +327,12 @@ def test(a: check.test) -> check.test:
                 @typechecked
                 def test(a: check.test):
                     pass
-                self.assertRaises(TypeError, test, value)
+                self.assertRaises(IncorrectArgument, test, value)
 
                 @typechecked
                 def test(a) -> check.test:
                     return value
-                self.assertRaises(TypeError, test, value)
+                self.assertRaises(IncorrectReturnType, test, value)
 
 class UnionTest(unittest.TestCase):