diff --git a/fdts/stm32mp13-fw-config.dtsi b/fdts/stm32mp13-fw-config.dtsi
index 28f7086c3..4f3bb726b 100644
--- a/fdts/stm32mp13-fw-config.dtsi
+++ b/fdts/stm32mp13-fw-config.dtsi
@@ -13,7 +13,7 @@
 #endif
 
 #define DDR_NS_BASE	STM32MP_DDR_BASE
-#define DDR_SEC_SIZE	0x02000000
+#define DDR_SEC_SIZE	STM32MP_DDR_S_SIZE
 #define DDR_SEC_BASE	(STM32MP_DDR_BASE + (DDR_SIZE - DDR_SEC_SIZE))
 #define DDR_NS_SIZE	(DDR_SEC_BASE - DDR_NS_BASE)