diff --git a/hw/onenand.c b/hw/onenand.c
index d63ecea..5e51089 100644
--- a/hw/onenand.c
+++ b/hw/onenand.c
@@ -355,6 +355,21 @@
             s->wpstatus = s->blockwp[b] = ONEN_LOCK_UNLOCKED;
         }
         break;
+    case 0x27:	/* Unlock All NAND array blocks */
+        s->intstatus |= ONEN_INT;
+
+        for (b = 0; b < s->blocks; b ++) {
+            if (b >= s->blocks) {
+                s->status |= ONEN_ERR_CMD;
+                break;
+            }
+            if (s->blockwp[b] == ONEN_LOCK_LOCKTIGHTEN)
+                break;
+
+            s->wpstatus = s->blockwp[b] = ONEN_LOCK_UNLOCKED;
+        }
+        break;
+
     case 0x2a:	/* Lock NAND array block(s) */
         s->intstatus |= ONEN_INT;