diff --git a/flask/app.py b/flask/app.py
index cc9a2f90..3204e13f 100644
--- a/flask/app.py
+++ b/flask/app.py
@@ -1478,7 +1478,7 @@ class Flask(_PackageBoundObject):
             rv = self.preprocess_request()
             if rv is None:
                 rv = self.dispatch_request()
-        except Exception, e:
+        except Exception as e:
             rv = self.handle_user_exception(e)
         response = self.make_response(rv)
         response = self.process_response(response)
@@ -1516,9 +1516,9 @@ class Flask(_PackageBoundObject):
             methods = []
             try:
                 adapter.match(method='--')
-            except MethodNotAllowed, e:
+            except MethodNotAllowed as e:
                 methods = e.valid_methods
-            except HTTPException, e:
+            except HTTPException as e:
                 pass
         rv = self.response_class()
         rv.allow.update(methods)
@@ -1626,7 +1626,7 @@ class Flask(_PackageBoundObject):
                 rv = handler(error, endpoint, values)
                 if rv is not None:
                     return rv
-            except BuildError, error:
+            except BuildError as error:
                 pass
 
         # At this point we want to reraise the exception.  If the error is
@@ -1807,7 +1807,7 @@ class Flask(_PackageBoundObject):
         with self.request_context(environ):
             try:
                 response = self.full_dispatch_request()
-            except Exception, e:
+            except Exception as e:
                 response = self.make_response(self.handle_exception(e))
             return response(environ, start_response)
 
diff --git a/flask/config.py b/flask/config.py
index 759fd488..80e9983e 100644
--- a/flask/config.py
+++ b/flask/config.py
@@ -127,7 +127,7 @@ class Config(dict):
         d.__file__ = filename
         try:
             execfile(filename, d.__dict__)
-        except IOError, e:
+        except IOError as e:
             if silent and e.errno in (errno.ENOENT, errno.EISDIR):
                 return False
             e.strerror = 'Unable to load configuration file (%s)' % e.strerror
diff --git a/flask/ctx.py b/flask/ctx.py
index 6b271687..a02c9a86 100644
--- a/flask/ctx.py
+++ b/flask/ctx.py
@@ -279,7 +279,7 @@ class RequestContext(object):
             url_rule, self.request.view_args = \
                 self.url_adapter.match(return_rule=True)
             self.request.url_rule = url_rule
-        except HTTPException, e:
+        except HTTPException as e:
             self.request.routing_exception = e
 
     def push(self):
diff --git a/flask/debughelpers.py b/flask/debughelpers.py
index 3ebd2f3e..504fab93 100644
--- a/flask/debughelpers.py
+++ b/flask/debughelpers.py
@@ -76,7 +76,7 @@ def attach_enctype_error_multidict(request):
         def __getitem__(self, key):
             try:
                 return oldcls.__getitem__(self, key)
-            except KeyError, e:
+            except KeyError as e:
                 if key not in request.form:
                     raise
                 raise DebugFilesKeyError(request, key)
diff --git a/flask/helpers.py b/flask/helpers.py
index d24dde6b..d68cb04b 100644
--- a/flask/helpers.py
+++ b/flask/helpers.py
@@ -301,7 +301,7 @@ def url_for(endpoint, **values):
     try:
         rv = url_adapter.build(endpoint, values, method=method,
                                force_external=external)
-    except BuildError, error:
+    except BuildError as error:
         # We need to inject the values again so that the app callback can
         # deal with that sort of stuff.
         values['_external'] = external
diff --git a/flask/testsuite/__init__.py b/flask/testsuite/__init__.py
index 5d86fa3d..084b3726 100644
--- a/flask/testsuite/__init__.py
+++ b/flask/testsuite/__init__.py
@@ -220,5 +220,5 @@ def main():
     """Runs the testsuite as command line application."""
     try:
         unittest.main(testLoader=BetterLoader(), defaultTest='suite')
-    except Exception, e:
+    except Exception as e:
         print 'Error: %s' % e
diff --git a/flask/testsuite/basic.py b/flask/testsuite/basic.py
index 5f6dbe4b..2836a1b6 100644
--- a/flask/testsuite/basic.py
+++ b/flask/testsuite/basic.py
@@ -256,7 +256,7 @@ class BasicFunctionalityTestCase(FlaskTestCase):
         def expect_exception(f, *args, **kwargs):
             try:
                 f(*args, **kwargs)
-            except RuntimeError, e:
+            except RuntimeError as e:
                 self.assert_(e.args and 'session is unavailable' in e.args[0])
             else:
                 self.assert_(False, 'expected exception')
@@ -629,7 +629,7 @@ class BasicFunctionalityTestCase(FlaskTestCase):
         c = app.test_client()
         try:
             c.get('/fail')
-        except KeyError, e:
+        except KeyError as e:
             self.assert_(isinstance(e, BadRequest))
         else:
             self.fail('Expected exception')
@@ -645,7 +645,7 @@ class BasicFunctionalityTestCase(FlaskTestCase):
         c = app.test_client()
         try:
             c.get('/fail')
-        except NotFound, e:
+        except NotFound as e:
             pass
         else:
             self.fail('Expected exception')
@@ -664,7 +664,7 @@ class BasicFunctionalityTestCase(FlaskTestCase):
         with app.test_client() as c:
             try:
                 c.post('/fail', data={'foo': 'index.txt'})
-            except DebugFilesKeyError, e:
+            except DebugFilesKeyError as e:
                 self.assert_('no file contents were transmitted' in str(e))
                 self.assert_('This was submitted: "index.txt"' in str(e))
             else:
@@ -755,7 +755,7 @@ class BasicFunctionalityTestCase(FlaskTestCase):
         try:
             with app.test_request_context():
                 flask.url_for('spam')
-        except BuildError, error:
+        except BuildError as error:
             pass
         try:
             raise RuntimeError('Test case where BuildError is not current.')
@@ -802,7 +802,7 @@ class BasicFunctionalityTestCase(FlaskTestCase):
             return None
         try:
             app.test_client().get('/')
-        except ValueError, e:
+        except ValueError as e:
             self.assert_equal(str(e), 'View function did not return a response')
             pass
         else:
@@ -843,7 +843,7 @@ class BasicFunctionalityTestCase(FlaskTestCase):
             rv = app.test_client().get('/', 'https://localhost.localdomain')
             # Werkzeug 0.8
             self.assert_equal(rv.status_code, 404)
-        except ValueError, e:
+        except ValueError as e:
             # Werkzeug 0.7
             self.assert_equal(str(e), "the server name provided " +
                     "('localhost.localdomain:443') does not match the " + \
@@ -854,7 +854,7 @@ class BasicFunctionalityTestCase(FlaskTestCase):
             rv = app.test_client().get('/', 'http://foo.localhost')
             # Werkzeug 0.8
             self.assert_equal(rv.status_code, 404)
-        except ValueError, e:
+        except ValueError as e:
             # Werkzeug 0.7
             self.assert_equal(str(e), "the server name provided " + \
                     "('localhost.localdomain') does not match the " + \
@@ -975,7 +975,7 @@ class BasicFunctionalityTestCase(FlaskTestCase):
             @app.route('/foo')
             def broken():
                 return 'Meh'
-        except AssertionError, e:
+        except AssertionError as e:
             self.assert_('A setup function was called' in str(e))
         else:
             self.fail('Expected exception')
@@ -1009,7 +1009,7 @@ class BasicFunctionalityTestCase(FlaskTestCase):
         with app.test_client() as c:
             try:
                 c.post('/foo', data={})
-            except AssertionError, e:
+            except AssertionError as e:
                 self.assert_('http://localhost/foo/' in str(e))
                 self.assert_('Make sure to directly send your POST-request '
                              'to this URL' in str(e))
diff --git a/flask/testsuite/blueprints.py b/flask/testsuite/blueprints.py
index ea047918..0399d48e 100644
--- a/flask/testsuite/blueprints.py
+++ b/flask/testsuite/blueprints.py
@@ -183,7 +183,7 @@ class ModuleTestCase(FlaskTestCase):
         with app.test_request_context():
             try:
                 flask.render_template('missing.html')
-            except TemplateNotFound, e:
+            except TemplateNotFound as e:
                 self.assert_equal(e.name, 'missing.html')
             else:
                 self.assert_(0, 'expected exception')
@@ -378,7 +378,7 @@ class BlueprintTestCase(FlaskTestCase):
         with app.test_request_context():
             try:
                 flask.render_template('missing.html')
-            except TemplateNotFound, e:
+            except TemplateNotFound as e:
                 self.assert_equal(e.name, 'missing.html')
             else:
                 self.assert_(0, 'expected exception')
diff --git a/flask/testsuite/config.py b/flask/testsuite/config.py
index bf72925b..0b2c65bd 100644
--- a/flask/testsuite/config.py
+++ b/flask/testsuite/config.py
@@ -57,7 +57,7 @@ class ConfigTestCase(FlaskTestCase):
             app = flask.Flask(__name__)
             try:
                 app.config.from_envvar('FOO_SETTINGS')
-            except RuntimeError, e:
+            except RuntimeError as e:
                 self.assert_("'FOO_SETTINGS' is not set" in str(e))
             else:
                 self.assert_(0, 'expected exception')
@@ -76,7 +76,7 @@ class ConfigTestCase(FlaskTestCase):
             try:
                 app = flask.Flask(__name__)
                 app.config.from_envvar('FOO_SETTINGS')
-            except IOError, e:
+            except IOError as e:
                 msg = str(e)
                 self.assert_(msg.startswith('[Errno 2] Unable to load configuration '
                                             'file (No such file or directory):'))
@@ -91,7 +91,7 @@ class ConfigTestCase(FlaskTestCase):
         app = flask.Flask(__name__)
         try:
             app.config.from_pyfile('missing.cfg')
-        except IOError, e:
+        except IOError as e:
             msg = str(e)
             self.assert_(msg.startswith('[Errno 2] Unable to load configuration '
                                         'file (No such file or directory):'))
@@ -141,7 +141,7 @@ class InstanceTestCase(FlaskTestCase):
         here = os.path.abspath(os.path.dirname(__file__))
         try:
             flask.Flask(__name__, instance_path='instance')
-        except ValueError, e:
+        except ValueError as e:
             self.assert_('must be absolute' in str(e))
         else:
             self.fail('Expected value error')
diff --git a/flask/testsuite/reqctx.py b/flask/testsuite/reqctx.py
index a93523e7..89a47728 100644
--- a/flask/testsuite/reqctx.py
+++ b/flask/testsuite/reqctx.py
@@ -58,7 +58,7 @@ class RequestContextTestCase(FlaskTestCase):
         try:
             with app.test_request_context('/', environ_overrides={'HTTP_HOST': 'localhost'}):
                 pass
-        except Exception, e:
+        except Exception as e:
             self.assert_(isinstance(e, ValueError))
             self.assert_equal(str(e), "the server name provided " +
                     "('localhost.localdomain:5000') does not match the " + \
@@ -68,7 +68,7 @@ class RequestContextTestCase(FlaskTestCase):
             app.config.update(SERVER_NAME='localhost')
             with app.test_request_context('/', environ_overrides={'SERVER_NAME': 'localhost'}):
                 pass
-        except ValueError, e:
+        except ValueError as e:
             raise ValueError(
                 "No ValueError exception should have been raised \"%s\"" % e
             )
@@ -77,7 +77,7 @@ class RequestContextTestCase(FlaskTestCase):
             app.config.update(SERVER_NAME='localhost:80')
             with app.test_request_context('/', environ_overrides={'SERVER_NAME': 'localhost:80'}):
                 pass
-        except ValueError, e:
+        except ValueError as e:
             raise ValueError(
                 "No ValueError exception should have been raised \"%s\"" % e
             )
diff --git a/flask/testsuite/testing.py b/flask/testsuite/testing.py
index 92e3f267..605078a7 100644
--- a/flask/testsuite/testing.py
+++ b/flask/testsuite/testing.py
@@ -106,7 +106,7 @@ class TestToolsTestCase(FlaskTestCase):
             try:
                 with c.session_transaction() as sess:
                     pass
-            except RuntimeError, e:
+            except RuntimeError as e:
                 self.assert_('Session backend did not open a session' in str(e))
             else:
                 self.fail('Expected runtime error')
@@ -130,7 +130,7 @@ class TestToolsTestCase(FlaskTestCase):
         try:
             with c.session_transaction() as s:
                 pass
-        except RuntimeError, e:
+        except RuntimeError as e:
             self.assert_('cookies' in str(e))
         else:
             self.fail('Expected runtime error')
diff --git a/flask/wrappers.py b/flask/wrappers.py
index d348ee0a..5f4e74a3 100644
--- a/flask/wrappers.py
+++ b/flask/wrappers.py
@@ -99,7 +99,7 @@ class Request(RequestBase):
                 if request_charset is not None:
                     return json.loads(self.data, encoding=request_charset)
                 return json.loads(self.data)
-            except ValueError, e:
+            except ValueError as e:
                 return self.on_json_loading_failed(e)
 
     def on_json_loading_failed(self, e):