diff --git a/docs/index.rst b/docs/index.rst
index 31fa423..c5b9543 100644
--- a/docs/index.rst
+++ b/docs/index.rst
@@ -66,19 +66,22 @@ used to escape the HTML):
     import houdini as h
     import misaka as m
     from pygments import highlight
-    from pygments.formatters import HtmlFormatter
+    from pygments.formatters import HtmlFormatter, ClassNotFound
     from pygments.lexers import get_lexer_by_name
 
     class HighlighterRenderer(m.HtmlRenderer):
         def blockcode(self, text, lang):
-            if not lang:
-                return '\n<pre><code>{}</code></pre>\n'.format(
-                    h.escape_html(text.strip()))
-
-            lexer = get_lexer_by_name(lang, stripall=True)
-            formatter = HtmlFormatter()
-
-            return highlight(text, lexer, formatter)
+            try:
+                lexer = get_lexer_by_name(lang, stripall=True)
+            except ClassNotFound:
+                lexer = None
+
+            if lexer:
+                formatter = HtmlFormatter()
+                return highlight(text, lexer, formatter)
+            # default
+            return '\n<pre><code>{}</code></pre>\n'.format(
+                                h.escape_html(text.strip()))
 
     renderer = HighlighterRenderer()
     md = m.Markdown(renderer, extensions=('fenced-code',))