diff --git a/httpie/httpie.py b/httpie/httpie.py
index 651e5933..793aecf6 100755
--- a/httpie/httpie.py
+++ b/httpie/httpie.py
@@ -27,10 +27,11 @@ class KeyValueType(object):
         self.separators = separators
 
     def __call__(self, string):
+        found = dict(
+            (string.find(sep), sep) for sep in self.separators
+                if string.find(sep) != -1 
+        )
 
-        found = {string.find(sep): sep
-                 for sep in self.separators
-                 if string.find(sep) != -1}
         if not found:
             raise argparse.ArgumentTypeError(
                 '"%s" is not a valid value' % string)
@@ -141,8 +142,8 @@ def main():
             verify=True if args.verify == 'yes' else args.verify,
             timeout=args.timeout,
             auth=(args.auth.key, args.auth.value) if args.auth else None,
-            proxies={proxy.key: proxy.value for proxy in args.proxy},
-            files={os.path.basename(f.name): f for f in args.file}
+            proxies=dict((p.key, p.value) for p in args.proxy),
+            files=dict((os.path.basename(f.name), f) for f in args.file),
         )
     except (KeyboardInterrupt, SystemExit) as e:
         sys.stderr.write('\n')