diff --git a/compressor/filters/css_default.py b/compressor/filters/css_default.py
index cf07fd7..28acfea 100644
--- a/compressor/filters/css_default.py
+++ b/compressor/filters/css_default.py
@@ -11,8 +11,15 @@ URL_PATTERN = re.compile(r'url\(([^\)]+)\)')
 
 
 class CssAbsoluteFilter(FilterBase):
-    def input(self, filename=None, basename=None, **kwargs):
+
+    def __init__(self, *args, **kwargs):
+        super(CssAbsoluteFilter, self).__init__(*args, **kwargs)
         self.root = settings.COMPRESS_ROOT
+        self.url = settings.COMPRESS_URL.rstrip('/')
+        self.url_path = self.url
+        self.has_scheme = False
+
+    def input(self, filename=None, basename=None, **kwargs):
         if filename is not None:
             filename = os.path.normcase(os.path.abspath(filename))
         if (not (filename and filename.startswith(self.root)) and
@@ -20,20 +27,16 @@ class CssAbsoluteFilter(FilterBase):
             return self.content
         self.path = basename.replace(os.sep, '/')
         self.path = self.path.lstrip('/')
-        self.url = settings.COMPRESS_URL.rstrip('/')
-        self.url_path = self.url
         self.mtime = get_hashed_mtime(filename)
-        self.has_http = False
-        if self.url.startswith('http://') or self.url.startswith('https://'):
-            self.has_http = True
+        if self.url.startswith(('http://', 'https://')):
+            self.has_scheme = True
             parts = self.url.split('/')
             self.url = '/'.join(parts[2:])
             self.url_path = '/%s' % '/'.join(parts[3:])
             self.protocol = '%s/' % '/'.join(parts[:2])
             self.host = parts[2]
-        self.directory_name = '/'.join([self.url, os.path.dirname(self.path)])
-        output = URL_PATTERN.sub(self.url_converter, self.content)
-        return output
+        self.directory_name = '/'.join((self.url, os.path.dirname(self.path)))
+        return URL_PATTERN.sub(self.url_converter, self.content)
 
     def find(self, basename):
         if settings.DEBUG and basename and staticfiles.finders:
@@ -41,7 +44,7 @@ class CssAbsoluteFilter(FilterBase):
 
     def guess_filename(self, url):
         local_path = url
-        if self.has_http:
+        if self.has_scheme:
             # COMPRESS_URL had a protocol, remove it and the hostname from our path.
             local_path = local_path.replace(self.protocol + self.host, "", 1)
         # Now, we just need to check if we can find the path from COMPRESS_URL in our url
@@ -56,24 +59,19 @@ class CssAbsoluteFilter(FilterBase):
         mtime = filename and get_hashed_mtime(filename) or self.mtime
         if mtime is None:
             return url
-        if (url.startswith('http://') or
-            url.startswith('https://') or
-            url.startswith('/')):
+        if url.startswith(('http://', 'https://', '/')):
             if "?" in url:
-                return "%s&%s" % (url, mtime)
-            return "%s?%s" % (url, mtime)
+                url = "%s&%s" % (url, mtime)
+            else:
+                url = "%s?%s" % (url, mtime)
         return url
 
     def url_converter(self, matchobj):
         url = matchobj.group(1)
         url = url.strip(' \'"')
-        if (url.startswith('http://') or
-            url.startswith('https://') or
-            url.startswith('/') or
-            url.startswith('data:')):
+        if url.startswith(('http://', 'https://', '/', 'data:')):
             return "url('%s')" % self.add_mtime(url)
-        full_url = '/'.join([str(self.directory_name), url])
-        full_url = posixpath.normpath(full_url)
-        if self.has_http:
+        full_url = posixpath.normpath('/'.join([self.directory_name, url]))
+        if self.has_scheme:
             full_url = "%s%s" % (self.protocol, full_url)
         return "url('%s')" % self.add_mtime(full_url)
diff --git a/compressor/tests/tests.py b/compressor/tests/tests.py
index 71e6466..eb0e058 100644
--- a/compressor/tests/tests.py
+++ b/compressor/tests/tests.py
@@ -219,6 +219,7 @@ class CssAbsolutizingTestCase(TestCase):
         filter = CssAbsoluteFilter(content)
         self.assertEqual(output, filter.input(filename=filename, basename='css/url/test.css'))
         settings.COMPRESS_URL = 'http://media.example.com/'
+        filter = CssAbsoluteFilter(content)
         filename = os.path.join(settings.COMPRESS_ROOT, 'css/url/test.css')
         output = "p { background: url('%simages/image.gif?%s') }" % (settings.COMPRESS_URL, get_hashed_mtime(filename))
         self.assertEqual(output, filter.input(filename=filename, basename='css/url/test.css'))
@@ -231,6 +232,7 @@ class CssAbsolutizingTestCase(TestCase):
         filter = CssAbsoluteFilter(content)
         self.assertEqual(output, filter.input(filename=filename, basename='css/url/test.css'))
         settings.COMPRESS_URL = 'https://media.example.com/'
+        filter = CssAbsoluteFilter(content)
         filename = os.path.join(settings.COMPRESS_ROOT, 'css/url/test.css')
         output = "p { background: url('%simages/image.gif?%s') }" % (settings.COMPRESS_URL, get_hashed_mtime(filename))
         self.assertEqual(output, filter.input(filename=filename, basename='css/url/test.css'))
@@ -243,6 +245,7 @@ class CssAbsolutizingTestCase(TestCase):
         filter = CssAbsoluteFilter(content)
         self.assertEqual(output, filter.input(filename=filename, basename='css/url/test.css'))
         settings.COMPRESS_URL = 'https://media.example.com/'
+        filter = CssAbsoluteFilter(content)
         output = "p { background: url('%simages/image.gif?%s') }" % (settings.COMPRESS_URL, get_hashed_mtime(filename))
         self.assertEqual(output, filter.input(filename=filename, basename='css/url/test.css'))