diff --git a/hw/net/dp8393x.c b/hw/net/dp8393x.c
index 9118364aa3..d1e147a82a 100644
--- a/hw/net/dp8393x.c
+++ b/hw/net/dp8393x.c
@@ -85,6 +85,7 @@ static const char *reg_names[] = {
 #define SONIC_MPT    0x2e
 #define SONIC_MDT    0x2f
 #define SONIC_DCR2   0x3f
+#define SONIC_REG_COUNT  0x40
 
 #define SONIC_CR_HTX     0x0001
 #define SONIC_CR_TXP     0x0002
@@ -158,7 +159,7 @@ struct dp8393xState {
 
     /* Registers */
     uint8_t cam[16][6];
-    uint16_t regs[0x40];
+    uint16_t regs[SONIC_REG_COUNT];
 
     /* Temporaries */
     uint8_t tx_buffer[0x10000];
@@ -972,7 +973,7 @@ static void dp8393x_realize(DeviceState *dev, Error **errp)
 
     address_space_init(&s->as, s->dma_mr, "dp8393x");
     memory_region_init_io(&s->mmio, OBJECT(dev), &dp8393x_ops, s,
-                          "dp8393x-regs", 0x40 << s->it_shift);
+                          "dp8393x-regs", SONIC_REG_COUNT << s->it_shift);
 
     s->nic = qemu_new_nic(&net_dp83932_info, &s->conf,
                           object_get_typename(OBJECT(dev)), dev->id, s);
@@ -987,7 +988,7 @@ static const VMStateDescription vmstate_dp8393x = {
     .minimum_version_id = 0,
     .fields = (VMStateField []) {
         VMSTATE_BUFFER_UNSAFE(cam, dp8393xState, 0, 16 * 6),
-        VMSTATE_UINT16_ARRAY(regs, dp8393xState, 0x40),
+        VMSTATE_UINT16_ARRAY(regs, dp8393xState, SONIC_REG_COUNT),
         VMSTATE_END_OF_LIST()
     }
 };