diff --git a/target/linux/mediatek/files-5.4/arch/arm64/boot/dts/mediatek/mt7986a.dtsi b/target/linux/mediatek/files-5.4/arch/arm64/boot/dts/mediatek/mt7986a.dtsi
index 820e8bb..81851a0 100644
--- a/target/linux/mediatek/files-5.4/arch/arm64/boot/dts/mediatek/mt7986a.dtsi
+++ b/target/linux/mediatek/files-5.4/arch/arm64/boot/dts/mediatek/mt7986a.dtsi
@@ -124,9 +124,9 @@
 		#size-cells = <2>;
 		ranges;
 
-		/* 192 KiB reserved for ARM Trusted Firmware (BL31) */
+		/* 256 KiB reserved for ARM Trusted Firmware (BL31) */
 		secmon_reserved: secmon@43000000 {
-			reg = <0 0x43000000 0 0x30000>;
+			reg = <0 0x43000000 0 0x40000>;
 			no-map;
 		};
 
diff --git a/target/linux/mediatek/files-5.4/arch/arm64/boot/dts/mediatek/mt7986b.dtsi b/target/linux/mediatek/files-5.4/arch/arm64/boot/dts/mediatek/mt7986b.dtsi
index 96c68a5..6fcfa57 100644
--- a/target/linux/mediatek/files-5.4/arch/arm64/boot/dts/mediatek/mt7986b.dtsi
+++ b/target/linux/mediatek/files-5.4/arch/arm64/boot/dts/mediatek/mt7986b.dtsi
@@ -124,9 +124,9 @@
 		#size-cells = <2>;
 		ranges;
 
-		/* 192 KiB reserved for ARM Trusted Firmware (BL31) */
+		/* 256 KiB reserved for ARM Trusted Firmware (BL31) */
 		secmon_reserved: secmon@43000000 {
-			reg = <0 0x43000000 0 0x30000>;
+			reg = <0 0x43000000 0 0x40000>;
 			no-map;
 		};