diff --git a/pkgs/os-specific/linux/kernel/common-config.nix b/pkgs/os-specific/linux/kernel/common-config.nix
index 28e640404ba1..6c0546285fd0 100644
--- a/pkgs/os-specific/linux/kernel/common-config.nix
+++ b/pkgs/os-specific/linux/kernel/common-config.nix
@@ -111,7 +111,9 @@ let
 
       # Enable crashkernel support
       PROC_VMCORE = yes;
-      HIGHMEM4G = lib.mkIf (stdenv.hostPlatform.isx86 && stdenv.hostPlatform.is32bit) yes;
+      HIGHMEM4G = lib.mkIf (stdenv.hostPlatform.isx86 && stdenv.hostPlatform.is32bit) (
+        whenAtLeast "6.15" yes
+      );
 
       # Track memory leaks and performance issues related to allocations.
       MEM_ALLOC_PROFILING = whenAtLeast "6.10" yes;
@@ -954,7 +956,7 @@ let
       KSM = yes;
       VIRT_DRIVERS = yes;
       # We need 64 GB (PAE) support for Xen guest support
-      HIGHMEM64G = {
+      HIGHMEM64G = whenOlder "6.15" {
         optional = true;
         tristate = lib.mkIf (!stdenv.hostPlatform.is64bit) "y";
       };