diff --git a/FreeDMR-SAMPLE.cfg b/FreeDMR-SAMPLE.cfg
index e720026..76e7813 100755
--- a/FreeDMR-SAMPLE.cfg
+++ b/FreeDMR-SAMPLE.cfg
@@ -36,6 +36,7 @@ PEER_URL: https://www.radioid.net/static/rptrs.json
 SUBSCRIBER_URL: https://www.radioid.net/static/users.json
 TGID_URL: http://downloads.freedmr.uk/downloads/talkgroup_ids.json
 STALE_DAYS: 7
+SUB_MAP_FILE:
 
 [MYSQL]
 USE_MYSQL: False
diff --git a/bridge_master.py b/bridge_master.py
index 7d406e0..1704dc6 100644
--- a/bridge_master.py
+++ b/bridge_master.py
@@ -417,7 +417,8 @@ def SubMapTrimmer():
     for _remove in _remove_list:
         SUB_MAP.pop(_remove)
     
-    subMapWrite()
+    if CONFIG['ALIASES']['SUB_MAP_FILE']:
+        subMapWrite()
  
     
         
@@ -2610,7 +2611,8 @@ if __name__ == '__main__':
         hblink_handler(_signal, _frame)
         logger.info('(GLOBAL) SHUTDOWN: ALL SYSTEM HANDLERS EXECUTED - STOPPING REACTOR')
         reactor.stop()
-        subMapWrite()
+        if CONFIG['ALIASES']['SUB_MAP_FILE']:
+            subMapWrite()
 
     # Set signal handers so that we can gracefully exit if need be
     for sig in [signal.SIGINT, signal.SIGTERM]:
@@ -2635,12 +2637,13 @@ if __name__ == '__main__':
     #SUB_MAP = {bytes_3(73578):('REP-1',1,time())}
     SUB_MAP = {}
     
-    try:
-        with open(CONFIG['ALIASES']['SUB_MAP_FILE']) as _json_file:
-            SUB_MAP = json.load(_json_file)
-    except:
-        logger.warning('(SUBSCRIBER) Cannot load SUB_MAP file')
-        #sys.exit('(SUBSCRIBER) TERMINATING: SUB_MAP file not found or invalid')
+    if CONFIG['ALIASES']['SUB_MAP_FILE']:
+        try:
+            with open(CONFIG['ALIASES']['SUB_MAP_FILE']) as _json_file:
+                SUB_MAP = json.load(_json_file)
+        except:
+            logger.warning('(SUBSCRIBER) Cannot load SUB_MAP file')
+            #sys.exit('(SUBSCRIBER) TERMINATING: SUB_MAP file not found or invalid')
     
     
     #Generator
diff --git a/docker-configs/docker-compose_install.sh b/docker-configs/docker-compose_install.sh
index 2647c7d..ac60d18 100644
--- a/docker-configs/docker-compose_install.sh
+++ b/docker-configs/docker-compose_install.sh
@@ -85,6 +85,7 @@ PEER_URL: https://www.radioid.net/static/rptrs.json
 SUBSCRIBER_URL: http://downloads.freedmr.uk/downloads/local_subscriber_ids.json
 TGID_URL: TGID_URL: http://downloads.freedmr.uk/downloads/talkgroup_ids.json
 STALE_DAYS: 7
+SUB_MAP_FILE:
 
 [MYSQL]
 USE_MYSQL: False