diff --git a/nixos/modules/system/boot/networkd.nix b/nixos/modules/system/boot/networkd.nix
index 2ff79f1cdc85..e275006cf843 100644
--- a/nixos/modules/system/boot/networkd.nix
+++ b/nixos/modules/system/boot/networkd.nix
@@ -1392,6 +1392,7 @@ let
           "Wash"
           "SplitGSO"
           "AckFilter"
+          "RTTSec"
         ])
         (assertValueOneOf "AutoRateIngress" boolValues)
         (assertInt "OverheadBytes")