diff --git a/envparse.py b/envparse.py
index e13b584..5591469 100644
--- a/envparse.py
+++ b/envparse.py
@@ -84,6 +84,10 @@ def __call__(self, var, default=NOTSET, cast=None, subcast=None,
                     subcast = params.get('subcast', subcast)
                 if default == NOTSET:
                     default = params.get('default', default)
+                if preprocessor is None:
+                    preprocessor = params.get('preprocessor', preprocessor)
+                if postprocessor is None:
+                    postprocessor = params.get('postprocessor', postprocessor)
             else:
                 if cast is None:
                     cast = params
diff --git a/tests/test_casts.py b/tests/test_casts.py
index ecb6bd8..071741d 100644
--- a/tests/test_casts.py
+++ b/tests/test_casts.py
@@ -123,6 +123,20 @@ def test_preprocessor():
     assert_type_value(str, 'FOO', env('STR', preprocessor=lambda
                                       v: v.upper()))
 
+def test_dict_preprocessor(monkeypatch):
+
+    monkeypatch.setenv('TEST', 'test_case')
+    e = Env(TEST=dict(cast=str, preprocessor=lambda x: x.upper()))
+    
+    assert_type_value(str, 'TEST_CASE', e('TEST'))
+
+def test_dict_postprocessor(monkeypatch):
+
+    monkeypatch.setenv('TEST', 'test')
+    e = Env(TEST=dict(cast=str, postprocessor=lambda x: x + "_case"))
+    
+    assert_type_value(str, 'test_case', e('TEST'))
+
 
 def test_postprocessor(monkeypatch):
     """