diff --git a/nix/culr-module.nix b/nix/culr-module.nix
index 0e2c066..5ee0b46 100644
--- a/nix/culr-module.nix
+++ b/nix/culr-module.nix
@@ -15,7 +15,7 @@ in {
       description = "colourising pattern";
     };
     palette = mkOption {
-      type = with types; nullOr (listOf str);
+      type = with types; listOf str;
       default = null;
       description = "palette to use in comma separated RGB hex eg. #0f0f0f";
     };
@@ -24,8 +24,8 @@ in {
   config = mkIf cfg.enable {
     environment.systemPackages = let inherit (pkgs) culr; in [culr];
     environment.sessionVariables = {
-      CULR_PATTERN = mkIf (cfg.pattern != null) cfg.pattern;
-      CULR_PALETTE = mkIf (cfg.palette != null) cfg.palette;
+      CULR_PATTERN = mkIf (cfg.pattern != []) cfg.pattern;
+      CULR_PALETTE = mkIf (cfg.palette != []) cfg.palette;
     };
   };
 }