diff --git a/pkgs/build-support/grsecurity/default.nix b/pkgs/build-support/grsecurity/default.nix
index 4379b1997ae2..ccd46e20654f 100644
--- a/pkgs/build-support/grsecurity/default.nix
+++ b/pkgs/build-support/grsecurity/default.nix
@@ -21,7 +21,7 @@ assert (kernel.version == grsecPatch.kver);
 
 overrideDerivation (kernel.override {
   inherit modDirVersion;
-  kernelPatches = [ grsecPatch ] ++ kernelPatches ++ (kernel.kernelPatches or []);
+  kernelPatches = lib.unique ([ grsecPatch ] ++ kernelPatches ++ (kernel.kernelPatches or []));
   extraConfig = ''
     GRKERNSEC y
     PAX y