diff --git a/plat/imx/imx8m/imx8mn/imx8mn_bl31_setup.c b/plat/imx/imx8m/imx8mn/imx8mn_bl31_setup.c
index 3000c23..5adbddd 100644
--- a/plat/imx/imx8m/imx8mn/imx8mn_bl31_setup.c
+++ b/plat/imx/imx8m/imx8mn/imx8mn_bl31_setup.c
@@ -182,7 +182,7 @@
 }
 
 #define MAP_BL31_TOTAL										   \
-	MAP_REGION_FLAT(BL31_BASE, BL31_LIMIT - BL31_BASE, MT_MEMORY | MT_RW | MT_SECURE)
+	MAP_REGION_FLAT(BL31_BASE, BL31_SIZE, MT_MEMORY | MT_RW | MT_SECURE)
 #define MAP_BL31_RO										   \
 	MAP_REGION_FLAT(BL_CODE_BASE, BL_CODE_END - BL_CODE_BASE, MT_MEMORY | MT_RO | MT_SECURE)
 #define MAP_COHERENT_MEM									   \
diff --git a/plat/imx/imx8m/imx8mn/include/platform_def.h b/plat/imx/imx8m/imx8mn/include/platform_def.h
index d4b1717..c75e250 100644
--- a/plat/imx/imx8m/imx8mn/include/platform_def.h
+++ b/plat/imx/imx8m/imx8mn/include/platform_def.h
@@ -8,8 +8,7 @@
 
 #include <lib/utils_def.h>
 #include <lib/xlat_tables/xlat_tables_v2.h>
-
-#include <lib/utils_def.h>
+#include <plat/common/common_def.h>
 
 #define PLATFORM_LINKER_FORMAT		"elf64-littleaarch64"
 #define PLATFORM_LINKER_ARCH		aarch64
@@ -42,7 +41,8 @@
 #define PLAT_SDEI_SGI_PRIVATE		U(9)
 
 #define BL31_BASE			U(0x960000)
-#define BL31_LIMIT			U(0x980000)
+#define BL31_SIZE			SZ_128K
+#define BL31_LIMIT			(BL31_BASE + BL31_SIZE)
 
 /* non-secure uboot base */
 #define PLAT_NS_IMAGE_OFFSET		U(0x40200000)