diff --git a/arch/nios2/boot/dts/10m50_devboard.dts b/arch/nios2/boot/dts/10m50_devboard.dts
index 4bb4dc1b52e9..d0831daa42c2 100644
--- a/arch/nios2/boot/dts/10m50_devboard.dts
+++ b/arch/nios2/boot/dts/10m50_devboard.dts
@@ -108,7 +108,7 @@
 			rx-fifo-depth = <8192>;
 			tx-fifo-depth = <8192>;
 			address-bits = <48>;
-			max-frame-size = <1518>;
+			max-frame-size = <1500>;
 			local-mac-address = [00 00 00 00 00 00];
 			altr,has-supplementary-unicast;
 			altr,enable-sup-addr = <1>;
diff --git a/arch/nios2/boot/dts/3c120_devboard.dts b/arch/nios2/boot/dts/3c120_devboard.dts
index 56f4b5df6d65..b0b4e45c1a4c 100644
--- a/arch/nios2/boot/dts/3c120_devboard.dts
+++ b/arch/nios2/boot/dts/3c120_devboard.dts
@@ -118,7 +118,7 @@
 				interrupt-names = "rx_irq", "tx_irq";
 				rx-fifo-depth = <8192>;
 				tx-fifo-depth = <8192>;
-				max-frame-size = <1518>;
+				max-frame-size = <1500>;
 				local-mac-address = [ 00 00 00 00 00 00 ];
 				phy-mode = "rgmii-id";
 				phy-handle = <&phy0>;