diff --git a/pkgs/top-level/linux-kernels.nix b/pkgs/top-level/linux-kernels.nix
index 57ae6c5f36a9..fba44186445e 100644
--- a/pkgs/top-level/linux-kernels.nix
+++ b/pkgs/top-level/linux-kernels.nix
@@ -683,7 +683,7 @@ in {
     # Update this when adding the newest kernel major version!
     linux_latest = packages.linux_6_9;
     linux_mptcp = throw "'linux_mptcp' has been moved to https://github.com/teto/mptcp-flake";
-    linux_rt_default = packages.linux_rt_5_4;
+    linux_rt_default = packages.linux_rt_5_15;
     linux_rt_latest = packages.linux_rt_6_6;
   } // { __attrsFailEvaluation = true; };