diff --git a/tests/test_difffiles.py b/tests/test_difffiles.py
index 544802ffc..c59d5c13d 100644
--- a/tests/test_difffiles.py
+++ b/tests/test_difffiles.py
@@ -319,8 +319,8 @@ def __check_diff(self, p, exp, revision=None):
         # TODO: Package.get_diff should return a consistent format
         #       (regardless of the used python version)
         def __canonise_diff(diff):
-            diff = re.sub('^@@ -(\d+) ', '@@ -\\1,\\1 ', diff, re.MULTILINE)
-            diff = re.sub('^(@@ -\d+,\d+) \+(\d+) ', '\\1 +\\2,\\2 ', diff, re.MULTILINE)
+            diff = re.sub('^@@ -(\d+) ', '@@ -\\1,\\1 ', diff, flags=re.MULTILINE)
+            diff = re.sub('^(@@ -\d+,\d+) \+(\d+) ', '\\1 +\\2,\\2 ', diff, flags=re.MULTILINE)
             return diff
 
         got = __canonise_diff(got)