diff --git a/Lib/test/test_urllib2.py b/Lib/test/test_urllib2.py
index 810ee5e6ea2..e7e80bc5dab 100644
--- a/Lib/test/test_urllib2.py
+++ b/Lib/test/test_urllib2.py
@@ -1340,21 +1340,22 @@ class HandlerTests(unittest.TestCase):
                 self.assertTrue(request.startswith(expected), repr(request))
 
     def test_proxy(self):
-        o = OpenerDirector()
-        ph = urllib.request.ProxyHandler(dict(http="proxy.example.com:3128"))
-        o.add_handler(ph)
-        meth_spec = [
-            [("http_open", "return response")]
-            ]
-        handlers = add_ordered_mock_handlers(o, meth_spec)
+        u = "proxy.example.com:3128"
+        for d in dict(http=u), dict(HTTP=u):
+            o = OpenerDirector()
+            ph = urllib.request.ProxyHandler(d)
+            o.add_handler(ph)
+            meth_spec = [
+                [("http_open", "return response")]
+                ]
+            handlers = add_ordered_mock_handlers(o, meth_spec)
 
-        req = Request("http://acme.example.com/")
-        self.assertEqual(req.host, "acme.example.com")
-        o.open(req)
-        self.assertEqual(req.host, "proxy.example.com:3128")
-
-        self.assertEqual([(handlers[0], "http_open")],
-                         [tup[0:2] for tup in o.calls])
+            req = Request("http://acme.example.com/")
+            self.assertEqual(req.host, "acme.example.com")
+            o.open(req)
+            self.assertEqual(req.host, u)
+            self.assertEqual([(handlers[0], "http_open")],
+                             [tup[0:2] for tup in o.calls])
 
     def test_proxy_no_proxy(self):
         os.environ['no_proxy'] = 'python.org'
diff --git a/Lib/urllib/request.py b/Lib/urllib/request.py
index f6ce9cb6d58..92c6a5d0150 100644
--- a/Lib/urllib/request.py
+++ b/Lib/urllib/request.py
@@ -800,6 +800,7 @@ class ProxyHandler(BaseHandler):
         assert hasattr(proxies, 'keys'), "proxies must be a mapping"
         self.proxies = proxies
         for type, url in proxies.items():
+            type = type.lower()
             setattr(self, '%s_open' % type,
                     lambda r, proxy=url, type=type, meth=self.proxy_open:
                         meth(r, proxy, type))
diff --git a/Misc/NEWS.d/next/Library/2019-05-22-04-52-35.bpo-25068.vR_rC-.rst b/Misc/NEWS.d/next/Library/2019-05-22-04-52-35.bpo-25068.vR_rC-.rst
new file mode 100644
index 00000000000..89de83bce02
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2019-05-22-04-52-35.bpo-25068.vR_rC-.rst
@@ -0,0 +1,2 @@
+:class:`urllib.request.ProxyHandler` now lowercases the keys of the passed
+dictionary.