diff --git a/board/sunxi/board_helper.c b/board/sunxi/board_helper.c
index 58645297..5b789065 100644
--- a/board/sunxi/board_helper.c
+++ b/board/sunxi/board_helper.c
@@ -104,6 +104,34 @@ int  __attribute__((weak)) update_bmu_info_to_kernel()
 int disp_lcd_param_update_to_kernel(void);
 int sunxi_drm_kernel_para_flush(void);
 
+int sunxi_fixup_external_fdt_dram(void *dtb_base)
+{
+	phys_size_t dram_size;
+
+	if (!dtb_base) {
+		pr_err("%s: dtb_base is NULL\n", __func__);
+		return -1;
+	}
+
+	dram_size = (phys_size_t)uboot_spare_head.boot_data.dram_scan_size *
+		    1024 * 1024;
+	if (!dram_size) {
+		pr_err("%s: invalid dram_scan_size %u MiB\n", __func__,
+		       uboot_spare_head.boot_data.dram_scan_size);
+		return -1;
+	}
+
+	gd->bd->bi_dram[0].size = dram_size;
+	if (arch_fixup_fdt(dtb_base) < 0) {
+		pr_err("%s: arch_fixup_fdt failed\n", __func__);
+		return -1;
+	}
+
+	tick_printf("sunxi: fixed external FDT DRAM size to %u MiB\n",
+		    uboot_spare_head.boot_data.dram_scan_size);
+	return 0;
+}
+
 #ifdef CONFIG_SUNXI_BOOT_PARAM
 int update_fdt_dram_para_from_bootpara(void *dtb_base)
 {
diff --git a/board/sunxi/board_helper.h b/board/sunxi/board_helper.h
index 4bd5e05d..2679d8c3 100644
--- a/board/sunxi/board_helper.h
+++ b/board/sunxi/board_helper.h
@@ -12,6 +12,7 @@
 
 void sunxi_dump(void *addr, unsigned int size);
 int  sunxi_update_fdt_para_for_kernel(void);
+int  sunxi_fixup_external_fdt_dram(void *dtb_base);
 int  sunxi_update_bootcmd(void);
 int  sunxi_update_partinfo(void);
 int sunxi_update_rotpk_info(void);
diff --git a/common/bootm.c b/common/bootm.c
index 188d16df..10be2f03 100644
--- a/common/bootm.c
+++ b/common/bootm.c
@@ -30,6 +30,8 @@
 #include <bootm.h>
 #include <image.h>
 
+int sunxi_fixup_external_fdt_dram(void *dtb_base);
+
 #ifndef CONFIG_SYS_BOOTM_LEN
 /* use 8MByte as default max gunzip size
  * want to change the CONFIG_SYS_BOOTM_LEN
@@ -363,6 +365,8 @@ int bootm_find_images(int flag, int argc, char * const argv[])
 		 */
 		images.ft_addr = (char *)simple_strtoul(argv[2], NULL, 16);
 		images.ft_len  = fdt_totalsize(images.ft_addr);
+		sunxi_fixup_external_fdt_dram(images.ft_addr);
+		images.ft_len  = fdt_totalsize(images.ft_addr);
 		printf("sunxi: using explicit FDT @ %p size 0x%lx\n",
 		       images.ft_addr, images.ft_len);
 	}