diff --git a/awx/api/serializers.py b/awx/api/serializers.py
index fd52c1d52f..e17fe41fd7 100644
--- a/awx/api/serializers.py
+++ b/awx/api/serializers.py
@@ -5645,13 +5645,12 @@ class InstanceSerializer(BaseSerializer):
     def get_reverse_peers(self, obj):
         return Instance.objects.prefetch_related('peers').filter(peers__in=obj.receptor_addresses.all()).values_list('id', flat=True)
 
-    # FIXME: protocol should be blank, null, or missing if there is no canonical address
     def get_protocol(self, obj):
         # note: don't create a different query for receptor addresses, as this is prefetched on the View for optimization
         for addr in obj.receptor_addresses.all():
             if addr.canonical:
                 return addr.protocol
-        return 'tcp'
+        return ""
 
     def get_consumed_capacity(self, obj):
         return obj.consumed_capacity