diff --git a/unidiff/constants.py b/unidiff/constants.py
index 5d82843..9601cd5 100644
--- a/unidiff/constants.py
+++ b/unidiff/constants.py
@@ -64,8 +64,8 @@
 
 RE_BINARY_DIFF = re.compile(
     r'^Binary files? '
-    '(?P<source_filename>[^\t]+?)(?:\t(?P<source_timestamp>[\s0-9:\+-]+))?'
-    '(?: and (?P<target_filename>[^\t]+?)(?:\t(?P<target_timestamp>[\s0-9:\+-]+))?)? (differ|has changed)')
+    r'(?P<source_filename>[^\t]+?)(?:\t(?P<source_timestamp>[\s0-9:\+-]+))?'
+    r'(?: and (?P<target_filename>[^\t]+?)(?:\t(?P<target_timestamp>[\s0-9:\+-]+))?)? (differ|has changed)')
 
 DEFAULT_ENCODING = 'UTF-8'