diff --git a/src/libCom/osi/os/WIN32/osdNetIntf.c b/src/libCom/osi/os/WIN32/osdNetIntf.c
index e980e4b40..0265a3994 100644
--- a/src/libCom/osi/os/WIN32/osdNetIntf.c
+++ b/src/libCom/osi/os/WIN32/osdNetIntf.c
@@ -231,9 +231,14 @@ epicsShareFunc void epicsShareAPI osiSockDiscoverBroadcastAddresses
             unsigned result = (addr & mask) | (bcast &~mask);
             pNewNode->addr.ia.sin_family = AF_INET;
             pNewNode->addr.ia.sin_addr.s_addr = result;
+            pNewNode->addr.ia.sin_port = 0u;
+            pNewNode->netMask.ia.sin_family = AF_INET;
+            pNewNode->netMask.ia.sin_addr.s_addr = mask;
+            pNewNode->netMask.ia.sin_port = 0u;
         } 
         else {
             pNewNode->addr.sa = pIfinfo->iiBroadcastAddress.Address;
+            memset ( &pNewNode->netMask, '\0', sizeof ( pNewNode->netMask ) );
         }
 
 		/*
diff --git a/src/libCom/osi/os/default/osdNetIntf.c b/src/libCom/osi/os/default/osdNetIntf.c
index 43dbeee1f..d8feebc30 100644
--- a/src/libCom/osi/os/default/osdNetIntf.c
+++ b/src/libCom/osi/os/default/osdNetIntf.c
@@ -181,6 +181,13 @@ epicsShareFunc void epicsShareAPI osiSockDiscoverBroadcastAddresses
                 continue;
             }
             pNewNode->addr.sa = pifreq->ifr_broadaddr;
+            status = socket_ioctl (socket, SIOCGIFNETMASK, pifreq);
+            if ( status ) {
+                errlogPrintf ("osiSockDiscoverInterfaces(): net intf \"%s\": net mask fetch fail\n", pifreq->ifr_name);
+                free ( pNewNode );
+                continue;
+            }
+            pNewNode->netMask.sa = pifreq->ifr_netmask;
         }
         else if ( pifreq->ifr_flags & IFF_POINTOPOINT ) {
             status = socket_ioctl ( socket, SIOCGIFDSTADDR, pifreq);
@@ -190,6 +197,7 @@ epicsShareFunc void epicsShareAPI osiSockDiscoverBroadcastAddresses
                 continue;
             }
             pNewNode->addr.sa = pifreq->ifr_dstaddr;
+            memset ( &pNewNode->netMask, '\0', sizeof ( pNewNode->netMask ) );
         }
         else {
             errlogPrintf ( "osiSockDiscoverInterfaces(): net intf \"%s\": not pt to pt or bcast?\n", pifreq->ifr_name );