diff --git a/sassutils/builder.py b/sassutils/builder.py
index faefba61..b07dfad7 100644
--- a/sassutils/builder.py
+++ b/sassutils/builder.py
@@ -23,7 +23,7 @@
 #: (:class:`re.RegexObject`) The regular expression pattern which matches to
 #: filenames of supported :const:`SUFFIXES`.
 SUFFIX_PATTERN = re.compile(
-    '[.](' + '|'.join(map(re.escape, sorted(SUFFIXES))) + ')$'
+    '[.](' + '|'.join(map(re.escape, sorted(SUFFIXES))) + ')$',
 )