diff --git a/requests/adapters.py b/requests/adapters.py
index 77badc7f..e065c759 100644
--- a/requests/adapters.py
+++ b/requests/adapters.py
@@ -206,7 +206,10 @@ class HTTPAdapter(BaseAdapter):
 
             conn = self.proxy_manager[proxy].connection_from_url(url)
         else:
-            conn = self.poolmanager.connection_from_url(url.lower())
+            # Only scheme should be lower case
+            parsed = urlparse(url)
+            url = parsed.geturl()
+            conn = self.poolmanager.connection_from_url(url)
 
         return conn
 
@@ -232,7 +235,7 @@ class HTTPAdapter(BaseAdapter):
         :param proxies: A dictionary of schemes to proxy URLs.
         """
         proxies = proxies or {}
-        scheme = urlparse(request.url).scheme.lower()
+        scheme = urlparse(request.url).scheme
         proxy = proxies.get(scheme)
 
         if proxy and scheme != 'https':
diff --git a/requests/sessions.py b/requests/sessions.py
index 175712f9..8aff5913 100644
--- a/requests/sessions.py
+++ b/requests/sessions.py
@@ -12,7 +12,7 @@ import os
 from collections import Mapping
 from datetime import datetime
 
-from .compat import cookielib, OrderedDict, urljoin, urlparse, urlunparse, builtin_str
+from .compat import cookielib, OrderedDict, urljoin, urlparse, builtin_str
 from .cookies import cookiejar_from_dict, extract_cookies_to_jar, RequestsCookieJar
 from .models import Request, PreparedRequest
 from .hooks import default_hooks, dispatch_hook
@@ -94,9 +94,7 @@ class SessionRedirectMixin(object):
 
             # The scheme should be lower case...
             parsed = urlparse(url)
-            parsed = (parsed.scheme.lower(), parsed.netloc, parsed.path,
-                      parsed.params, parsed.query, parsed.fragment)
-            url = urlunparse(parsed)
+            url = parsed.geturl()
 
             # Facilitate non-RFC2616-compliant 'location' headers
             # (e.g. '/path/to/resource' instead of 'http://domain.tld/path/to/resource')