diff --git a/src/ca/client/udpiiu.cpp b/src/ca/client/udpiiu.cpp
index e4e8bd31f..dcdb4f6af 100644
--- a/src/ca/client/udpiiu.cpp
+++ b/src/ca/client/udpiiu.cpp
@@ -163,6 +163,19 @@ udpiiu::udpiiu (
         throwWithLocation ( noSocket () );
     }
 
+#ifdef IP_ADD_MEMBERSHIP
+    {
+        int flag = 1;
+        if(setsockopt(this->sock, IPPROTO_IP, IP_MULTICAST_LOOP, &flag, sizeof(flag))==-1)
+        {
+            char sockErrBuf[64];
+            epicsSocketConvertErrnoToString (
+                sockErrBuf, sizeof ( sockErrBuf ) );
+            errlogPrintf("CAC: failed to set mcast loopback\n");
+        }
+    }
+#endif
+
     int boolValue = true;
     int status = setsockopt ( this->sock, SOL_SOCKET, SO_BROADCAST, 
                 (char *) &boolValue, sizeof ( boolValue ) );