diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 2bfd187bc5133d3fbc2a7116bca81528d52bdd98..d747e586c18e00b56c7f02616d5e90db47f5f1dc 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -2375,15 +2375,27 @@ static void spapr_phb_placement(sPAPRMachineState *spapr, uint32_t index,
                                 unsigned n_dma, uint32_t *liobns, Error **errp)
 {
     const uint64_t base_buid = 0x800000020000000ULL;
-    const hwaddr phb0_base = 0x10000000000ULL; /* 1 TiB */
     const hwaddr phb_spacing = 0x1000000000ULL; /* 64 GiB */
     const hwaddr mmio_offset = 0xa0000000; /* 2 GiB + 512 MiB */
     const hwaddr pio_offset = 0x80000000; /* 2 GiB */
     const uint32_t max_index = 255;
+    const hwaddr phb0_alignment = 0x10000000000ULL; /* 1 TiB */
 
-    hwaddr phb_base;
+    uint64_t ram_top = MACHINE(spapr)->ram_size;
+    hwaddr phb0_base, phb_base;
     int i;
 
+    /* Do we have hotpluggable memory? */
+    if (MACHINE(spapr)->maxram_size > ram_top) {
+        /* Can't just use maxram_size, because there may be an
+         * alignment gap between normal and hotpluggable memory
+         * regions */
+        ram_top = spapr->hotplug_memory.base +
+            memory_region_size(&spapr->hotplug_memory.mr);
+    }
+
+    phb0_base = QEMU_ALIGN_UP(ram_top, phb0_alignment);
+
     if (index > max_index) {
         error_setg(errp, "\"index\" for PAPR PHB is too large (max %u)",
                    max_index);