diff --git a/PDP11/pdp11_io_lib.c b/PDP11/pdp11_io_lib.c
index 0ddb4442..324a28a6 100644
--- a/PDP11/pdp11_io_lib.c
+++ b/PDP11/pdp11_io_lib.c
@@ -617,7 +617,10 @@ for (mr = mstart + 1; mr <= mend; mr++) {
         continue;
         }
     if (same_start != mr - 1)
-        fprintf (st, "%s-MAP[%04X thru %04X] same as above\n", busname, same_start + 1, mr - 1);
+        if (same_start + 1 == mr - 1)
+            fprintf (st, "%s-MAP[%04X] same as above\n", busname, same_start + 1);
+        else
+            fprintf (st, "%s-MAP[%04X thru %04X] same as above\n", busname, same_start + 1, mr - 1);
     fprintf (st, "%s-MAP[%04X] = %08X%s\n", busname, mr, busmap[mr], desc);
     same_start = mr;
     same_val = busmap[mr];