diff --git a/arch/arm64/src/qemu/qemu_boot.c b/arch/arm64/src/qemu/qemu_boot.c
index 0b1eafaa89..798b6a320c 100644
--- a/arch/arm64/src/qemu/qemu_boot.c
+++ b/arch/arm64/src/qemu/qemu_boot.c
@@ -52,11 +52,11 @@
 static const struct arm_mmu_region mmu_regions[] =
 {
   MMU_REGION_FLAT_ENTRY("DEVICE_REGION",
-                        CONFIG_DEVICEIO_BASEADDR, MB(512),
+                        CONFIG_DEVICEIO_BASEADDR, CONFIG_DEVICEIO_SIZE,
                         MT_DEVICE_NGNRNE | MT_RW | MT_SECURE),
 
   MMU_REGION_FLAT_ENTRY("DRAM0_S0",
-                        CONFIG_RAMBANK1_ADDR, MB(512),
+                        CONFIG_RAMBANK1_ADDR, CONFIG_RAMBANK1_SIZE,
                         MT_NORMAL | MT_RW | MT_SECURE),
 };