diff --git a/modules/programs/parallel.nix b/modules/programs/parallel.nix
index 4bb39a248..3ae7581d6 100644
--- a/modules/programs/parallel.nix
+++ b/modules/programs/parallel.nix
@@ -20,7 +20,7 @@ in
   options.programs.parallel = {
     enable = mkEnableOption "GNU Parallel";
 
-    package = lib.mkPackageOption pkgs "parallel-full" { };
+    package = lib.mkPackageOption pkgs "parallel-full" { nullable = true; };
 
     will-cite = mkOption {
       type = types.bool;
@@ -33,7 +33,7 @@ in
 
   config = mkIf cfg.enable {
     home = {
-      packages = [ cfg.package ];
+      packages = lib.mkIf (cfg.package != null) [ cfg.package ];
       file.".parallel/will-cite" = mkIf cfg.will-cite {
         text = "generated by home manager (programs.parallel.will-cite)";
       };