diff --git a/startup.script_common b/startup.script_common
index 6b44463..cdac6cd 100644
--- a/startup.script_common
+++ b/startup.script_common
@@ -136,10 +136,11 @@ require "misc", getenv("misc_VERSION")
 
 # Run Channel Access only on 1st network port
 putenv "EPICS_CA_AUTO_ADDR_LIST=NO"
-putenv bootInfo("EPICS_CA_ADDR_LIST=%B")
+putenv getenv("EPICS_CA_ADDR_LIST") ? "" : bootInfo("EPICS_CA_ADDR_LIST=%B")
 putenv bootInfo("EPICS_CAS_INTF_ADDR_LIST=%e")
 putenv "EPICS_CAS_AUTO_BEACON_ADDR_LIST=NO"
-putenv bootInfo("EPICS_CAS_BEACON_ADDR_LIST=%B")
+sprintf STRINGBUFFER, getenv("EPICS_CAS_BEACON_ADDR_LIST") ? "" : "EPICS_CAS_BEACON_ADDR_LIST=%s", getenv("EPICS_CA_ADDR_LIST")
+putenv STRINGBUFFER
 
 # EPICS 3.13 needs this to not use synchronized timestamps
 sprintf STRINGBUFFER, R3_13 ? "TSconfigure(0,10,10,18323,18322,250,1)" : ";"