diff --git a/markdown/extensions/admonition.py b/markdown/extensions/admonition.py
index 76e0fb588..9eab9c7e5 100644
--- a/markdown/extensions/admonition.py
+++ b/markdown/extensions/admonition.py
@@ -39,10 +39,13 @@ def extendMarkdown(self, md, md_globals):
 
 class AdmonitionProcessor(BlockProcessor):
 
-    CLASSNAME = 'admonition'
-    CLASSNAME_TITLE = 'admonition-title'
     RE = re.compile(r'(?:^|\n)!!!\ ?([\w\-]+)(?:\ "(.*?)")?')
 
+    def __init__(self, parser, classname='admonition', classname_title='admonition-title'):
+        self.CLASSNAME = classname
+        self.CLASSNAME_TITLE = classname_title
+        BlockProcessor.__init__(self, parser)
+
     def test(self, parent, block):
         sibling = self.lastChild(parent)
         return self.RE.search(block) or \