diff --git a/configs/qemu_arm_vexpress_defconfig b/configs/qemu_arm_vexpress_defconfig
index f99b87c17a..a106530ec8 100644
--- a/configs/qemu_arm_vexpress_defconfig
+++ b/configs/qemu_arm_vexpress_defconfig
@@ -16,6 +16,8 @@ BR2_TARGET_ROOTFS_EXT2=y
 # Image
 BR2_ROOTFS_POST_IMAGE_SCRIPT="board/qemu/post-image.sh"
 BR2_ROOTFS_POST_SCRIPT_ARGS="$(BR2_DEFCONFIG)"
+# Qemu >= 5.1 requires an SD card size to be a power of 2, e.g. 64 MiB.
+BR2_TARGET_ROOTFS_EXT2_SIZE="64M"
 
 # Linux headers same as kernel, a 5.4 series
 BR2_PACKAGE_HOST_LINUX_HEADERS_CUSTOM_5_4=y