diff --git a/B5500/b5500_urec.c b/B5500/b5500_urec.c
index b158655..b911dcc 100644
--- a/B5500/b5500_urec.c
+++ b/B5500/b5500_urec.c
@@ -377,11 +377,13 @@ cdr_srv(UNIT *uptr) {
                                chan_set_parity(chan);
                         }
                         break;
-            case 0111:
-                        ch = 0;
-                        /* Handle invalid punch */
-                        chan_set_parity(chan);
-                        break;  /* Translate ? to error*/
+            case 017:
+                        if (data->image[uptr->u4] == 0x006) {
+                            ch = 0;
+                            /* Handle invalid punch */
+                            chan_set_parity(chan);
+                            break;  /* Translate ? to error*/
+                        }
             }
         }
         sim_debug(DEBUG_DATA, &cdr_dev, "cdr %d: Char > %03o '%c' %d\n", u, ch,