diff --git a/lib/request/basic.py b/lib/request/basic.py
index 53e38e69b..eabf525f9 100755
--- a/lib/request/basic.py
+++ b/lib/request/basic.py
@@ -15,6 +15,7 @@ import zlib
 
 from lib.core.common import extractErrorMessage
 from lib.core.common import extractRegexResult
+from lib.core.common import getPublicTypeMembers
 from lib.core.common import getUnicode
 from lib.core.common import readInput
 from lib.core.common import resetCookieJar
@@ -53,7 +54,27 @@ def forgeHeaders(items=None):
     headers = dict(conf.httpHeaders)
     headers.update(items or {})
 
-    headers = dict(("-".join(_.capitalize() for _ in key.split('-')), value) for (key, value) in headers.items())
+    class _str(str):
+        def capitalize(self):
+            return _str(self)
+
+        def title(self):
+            return _str(self)
+
+    _ = headers
+    headers = {}
+    for key, value in _.items():
+        success = False
+        if key.upper() not in (_.upper() for _ in getPublicTypeMembers(HTTP_HEADER, True)):
+            try:
+                headers[_str(key)] = value  # dirty hack for http://bugs.python.org/issue12455
+            except UnicodeEncodeError:      # don't do the hack on non-ASCII header names (they have to be properly encoded later on)
+                pass
+            else:
+                success = True
+        if not success:
+            key = '-'.join(_.capitalize() for _ in key.split('-'))
+            headers[key] = value
 
     if conf.cj:
         if HTTP_HEADER.COOKIE in headers: