diff --git a/hw/block/nvme.c b/hw/block/nvme.c
index a21eeca2fb..c1476e8b2a 100644
--- a/hw/block/nvme.c
+++ b/hw/block/nvme.c
@@ -53,6 +53,9 @@
 #include "trace.h"
 #include "nvme.h"
 
+#define NVME_REG_SIZE 0x1000
+#define NVME_DB_SIZE  4
+
 #define NVME_GUEST_ERR(trace, fmt, ...) \
     do { \
         (trace_##trace)(__VA_ARGS__); \
@@ -1401,7 +1404,9 @@ static void nvme_realize(PCIDevice *pci_dev, Error **errp)
     pcie_endpoint_cap_init(pci_dev, 0x80);
 
     n->num_namespaces = 1;
-    n->reg_size = pow2ceil(0x1004 + 2 * (n->num_queues + 1) * 4);
+
+    /* num_queues is really number of pairs, so each has two doorbells */
+    n->reg_size = pow2ceil(NVME_REG_SIZE + 2 * n->num_queues * NVME_DB_SIZE);
     n->ns_size = bs_size / (uint64_t)n->num_namespaces;
 
     n->namespaces = g_new0(NvmeNamespace, n->num_namespaces);