diff --git a/imlac/imlac_dp.c b/imlac/imlac_dp.c
index 2265b9bc..7d638f42 100644
--- a/imlac/imlac_dp.c
+++ b/imlac/imlac_dp.c
@@ -149,7 +149,8 @@ dp_iot (uint16 insn, uint16 AC)
   }
   if ((insn & 0772) == 0002) { /* DLA */
     sim_debug (DBG, &dp_dev, "DPC set to %06o\n", AC & memmask);
-    DPC |= AC & memmask;
+    DPC = AC & memmask;
+    BLOCK = (AC >> 12) & 3;
   }
   if ((insn & 0771) == 0011) { /* CTB */
     ;