diff --git a/ietf/meeting/views.py b/ietf/meeting/views.py
index 95a444340..395a665d3 100644
--- a/ietf/meeting/views.py
+++ b/ietf/meeting/views.py
@@ -171,11 +171,11 @@ def current_materials(request):
 def materials_document(request, document, num=None, ext=None):
     if num is None:
         num = get_meeting(num).number
-    if (re.search('^\w+-\d+-.+-\d\d$', document) or
-        re.search('^\w+-interim-\d+-.+-\d\d-\d\d$', document) or
-        re.search('^\w+-interim-\d+-.+-sess[a-z]-\d\d$', document) or
-        re.search('^minutes-interim-\d+-.+-\d\d$', document) or
-        re.search('^slides-interim-\d+-.+-\d\d$', document)):
+    if (re.search(r'^\w+-\d+-.+-\d\d$', document) or
+        re.search(r'^\w+-interim-\d+-.+-\d\d-\d\d$', document) or
+        re.search(r'^\w+-interim-\d+-.+-sess[a-z]-\d\d$', document) or
+        re.search(r'^minutes-interim-\d+-.+-\d\d$', document) or
+        re.search(r'^slides-interim-\d+-.+-\d\d$', document)):
         name, rev = document.rsplit('-', 1)
     else:
         name, rev = document, None
diff --git a/ietf/utils/text.py b/ietf/utils/text.py
index 131f13fa7..d82a2fcb1 100644
--- a/ietf/utils/text.py
+++ b/ietf/utils/text.py
@@ -23,8 +23,8 @@ def xslugify(value):
     (I.e., does the same as slugify, but also converts slashes to dashes.)
     """
     value = unicodedata.normalize('NFKD', value).encode('ascii', 'ignore').decode('ascii')
-    value = re.sub('[^\w\s/-]', '', value).strip().lower()
-    return mark_safe(re.sub('[-\s/]+', '-', value))
+    value = re.sub(r'[^\w\s/-]', '', value).strip().lower()
+    return mark_safe(re.sub(r'[-\s/]+', '-', value))
 
 def strip_prefix(text, prefix):
     if text.startswith(prefix):