diff --git a/VAX/vax410_sysdev.c b/VAX/vax410_sysdev.c
index c51dd0ba..b07c67a1 100644
--- a/VAX/vax410_sysdev.c
+++ b/VAX/vax410_sysdev.c
@@ -483,6 +483,14 @@ switch (rg) {
         val = VAX410_SID | VAX410_UREV;
         break;
 
+    case MT_ICR:                                        /* for NetBSD */
+        val = 0;
+        break;
+
+    case MT_TXCS:                                       /* for Ultrix */
+        val = 0;
+        break;
+
     default:
         RSVD_OPND_FAULT(ReadIPR);
         }
@@ -515,6 +523,9 @@ switch (rg) {
         conpsl = val;
         break;
 
+    case MT_TXCS:                                       /* for Ultrix */
+        break;
+
     default:
         RSVD_OPND_FAULT(WriteIPR);
         }