diff --git a/awx/api/serializers.py b/awx/api/serializers.py
index 77e1bf37c1..b0f56077e9 100644
--- a/awx/api/serializers.py
+++ b/awx/api/serializers.py
@@ -4934,7 +4934,7 @@ class InstanceSerializer(BaseSerializer):
                     MaxLengthValidator(limit_value=250),
                     validators.UniqueValidator(queryset=Instance.objects.all()),
                     RegexValidator(
-                        regex='^localhost$|^127(?:\.[0-9]+){0,2}\.[0-9]+$|^(?:0*\:)*?:?0*1$',
+                        regex=r'^localhost$|^127(?:\.[0-9]+){0,2}\.[0-9]+$|^(?:0*\:)*?:?0*1$',
                         flags=re.IGNORECASE,
                         inverse_match=True,
                         message="hostname cannot be localhost or 127.0.0.1",