diff --git a/src/servicex_did_finder_lib/communication.py b/src/servicex_did_finder_lib/communication.py
index 5f1cc8a..a0200d0 100644
--- a/src/servicex_did_finder_lib/communication.py
+++ b/src/servicex_did_finder_lib/communication.py
@@ -57,7 +57,8 @@ async def run_file_fetch_loop(did: str, servicex: ServiceXAdapter, info: Dict[st
         servicex.post_status_update(f'Completed load of file in {elapsed_time} seconds')
 
 
-def rabbit_mq_callback(user_callback: UserDIDHandler, channel, method, properties, body):
+def rabbit_mq_callback(user_callback: UserDIDHandler, channel, method, properties, body,
+                       file_prefix=None):
     '''rabbit_mq_callback Respond to RabbitMQ Message
 
     When a request to resolve a DID comes into the DID finder, we
@@ -70,6 +71,7 @@ def rabbit_mq_callback(user_callback: UserDIDHandler, channel, method, propertie
         method ([type]): Delivery method
         properties ([type]): Properties of the message
         body ([type]): The body (json for us) of the message
+        file_prefix([str]): Prefix to put in front of file paths to enable use of Cache service
     '''
     request_id = None  # set this in case we get an exception while loading request
     try:
@@ -78,7 +80,7 @@ def rabbit_mq_callback(user_callback: UserDIDHandler, channel, method, propertie
         did = did_request['did']
         request_id = did_request['request_id']
         __logging.info(f'Received DID request {did_request}', extra={'requestId': request_id})
-        servicex = ServiceXAdapter(did_request['service-endpoint'])
+        servicex = ServiceXAdapter(did_request['service-endpoint'], file_prefix)
         servicex.post_status_update("DID Request received")
 
         info = {
@@ -105,7 +107,9 @@ def rabbit_mq_callback(user_callback: UserDIDHandler, channel, method, propertie
 
 
 def init_rabbit_mq(user_callback: UserDIDHandler,
-                   rabbitmq_url: str, queue_name: str, retries: int, retry_interval: float):
+                   rabbitmq_url: str, queue_name: str, retries: int,
+                   retry_interval: float,
+                   file_prefix: str = None):
     rabbitmq = None
     retry_count = 0
 
@@ -120,7 +124,7 @@ def init_rabbit_mq(user_callback: UserDIDHandler,
             _channel.basic_consume(queue=queue_name,
                                    auto_ack=False,
                                    on_message_callback=lambda c, m, p, b:
-                                   rabbit_mq_callback(user_callback, c, m, p, b))
+                                   rabbit_mq_callback(user_callback, c, m, p, b, file_prefix))
             _channel.start_consuming()
 
         except pika.exceptions.AMQPConnectionError:  # type: ignore
diff --git a/src/servicex_did_finder_lib/servicex_adaptor.py b/src/servicex_did_finder_lib/servicex_adaptor.py
index aaaeaab..cb6f769 100644
--- a/src/servicex_did_finder_lib/servicex_adaptor.py
+++ b/src/servicex_did_finder_lib/servicex_adaptor.py
@@ -35,8 +35,9 @@
 
 
 class ServiceXAdapter:
-    def __init__(self, endpoint):
+    def __init__(self, endpoint, file_prefix=None):
         self.endpoint = endpoint
+        self.file_prefix = file_prefix
 
         self.logger = logging.getLogger(__name__)
         self.logger.addHandler(logging.NullHandler())
@@ -61,6 +62,9 @@ def post_status_update(self, status_msg, severity="info"):
             self.logger.error(f'After {attempts} tries, failed to send ServiceX App a status '
                               f'message: {str(status_msg)} - Ignoring error.')
 
+    def _prefix_file(self, file_path):
+        return file_path if not self.file_prefix else self.file_prefix+file_path
+
     def put_file_add(self, file_info):
         success = False
         attempts = 0
@@ -68,7 +72,7 @@ def put_file_add(self, file_info):
             try:
                 mesg = {
                     "timestamp": datetime.now().isoformat(),
-                    "file_path": file_info['file_path'],
+                    "file_path": self._prefix_file(file_info['file_path']),
                     'adler32': file_info['adler32'],
                     'file_size': file_info['file_size'],
                     'file_events': file_info['file_events']
diff --git a/tests/servicex_did_finder_lib/test_servicex_did.py b/tests/servicex_did_finder_lib/test_servicex_did.py
index 222ccf2..4f01528 100644
--- a/tests/servicex_did_finder_lib/test_servicex_did.py
+++ b/tests/servicex_did_finder_lib/test_servicex_did.py
@@ -1,4 +1,8 @@
+import json
+
+import responses
 from servicex_did_finder_lib import __version__
+from servicex_did_finder_lib.servicex_adaptor import ServiceXAdapter
 
 
 def test_version():
@@ -23,3 +27,21 @@ def test_put_file_add():
     assert submitted['file_events'] == 3141
     assert submitted['file_size'] == 1024
 
+
+@responses.activate
+def test_put_file_add_with_prefix():
+    responses.add(responses.PUT, 'http://servicex.org/files', status=206)
+    sx = ServiceXAdapter("http://servicex.org", "xcache123:")
+    sx.put_file_add({
+        'file_path': 'root://foo.bar.ROOT',
+        'adler32': '32',
+        'file_size': 1024,
+        'file_events': 3141
+    })
+
+    assert len(responses.calls) == 1
+    submitted = json.loads(responses.calls[0].request.body)
+    assert submitted['file_path'] == 'xcache123:root://foo.bar.ROOT'
+    assert submitted['adler32'] == '32'
+    assert submitted['file_events'] == 3141
+    assert submitted['file_size'] == 1024