diff --git a/hw/m68k/mcf5208.c b/hw/m68k/mcf5208.c
index ec14096aa4..b6677ad6bc 100644
--- a/hw/m68k/mcf5208.c
+++ b/hw/m68k/mcf5208.c
@@ -4,6 +4,14 @@
  * Copyright (c) 2007 CodeSourcery.
  *
  * This code is licensed under the GPL
+ *
+ * This file models both the MCF5208 SoC, and the
+ * MCF5208EVB evaluation board. For details see
+ *
+ * "MCF5208 Reference Manual"
+ * https://www.nxp.com/docs/en/reference-manual/MCF5208RM.pdf
+ * "M5208EVB-RevB 32-bit Microcontroller User Manual"
+ * https://www.nxp.com/docs/en/reference-manual/M5208EVBUM.pdf
  */
 
 #include "qemu/osdep.h"
@@ -158,7 +166,7 @@ static uint64_t m5208_sys_read(void *opaque, hwaddr addr,
         {
             int n;
             for (n = 0; n < 32; n++) {
-                if (current_machine->ram_size < (2u << n)) {
+                if (current_machine->ram_size < (2ULL << n)) {
                     break;
                 }
             }
diff --git a/hw/nubus/nubus-device.c b/hw/nubus/nubus-device.c
index be4cb24696..26fbcf29a2 100644
--- a/hw/nubus/nubus-device.c
+++ b/hw/nubus/nubus-device.c
@@ -35,6 +35,13 @@ static void nubus_device_realize(DeviceState *dev, Error **errp)
     uint8_t *rom_ptr;
     int ret;
 
+    if (nd->slot < 0 || nd->slot >= NUBUS_SLOT_NB) {
+        error_setg(errp,
+                   "'slot' value %d out of range (must be between 0 and %d)",
+                   nd->slot, NUBUS_SLOT_NB - 1);
+        return;
+    }
+
     /* Super */
     slot_offset = nd->slot * NUBUS_SUPER_SLOT_SIZE;