diff --git a/grappelli/settings.py b/grappelli/settings.py
index b8a07b310..6a1fb95ce 100644
--- a/grappelli/settings.py
+++ b/grappelli/settings.py
@@ -24,7 +24,7 @@
 # SWITCH_USER_ORIGINAL: Defines if a user is a valid target.
 # Gets a user object and returns True/False.
 SWITCH_USER_TARGET = getattr(settings, "GRAPPELLI_SWITCH_USER_TARGET", lambda original_user, user: user.is_staff and not user.is_superuser)
-SWITCH_USER_REGEX = getattr(settings, "GRAPPELLI_SWITCH_USER_REGEX", "\d+")
+SWITCH_USER_REGEX = getattr(settings, "GRAPPELLI_SWITCH_USER_REGEX", r"\d+")
 
 # CLEAN INPUT TYPES
 # Replaces input types: search, email, url, tel, number, range, date