diff --git a/nixos/modules/services/networking/knot-resolver.nix b/nixos/modules/services/networking/knot-resolver.nix
index f669aa3db383..9ae940182a30 100644
--- a/nixos/modules/services/networking/knot-resolver.nix
+++ b/nixos/modules/services/networking/knot-resolver.nix
@@ -112,8 +112,15 @@ in
     };
     users.groups.knot-resolver = { };
     networking.resolvconf.useLocalResolver = lib.mkDefault true;
-    assertions = lib.optionals (lib.versions.major cfg.package.version == 5) [
-      "services.knot-resolver only works with knot-resolver 6 or later. Please use services.kresd for knot-resolver 5."
+
+    assertions = [
+      {
+        assertion = lib.versionAtLeast cfg.package.version "6.0.0";
+        message = ''
+          services.knot-resolver only works with knot-resolver 6 or later.
+          Please use services.kresd for knot-resolver 5.
+        '';
+      }
     ];
 
     environment = {
diff --git a/nixos/modules/services/networking/kresd.nix b/nixos/modules/services/networking/kresd.nix
index 88f6526d19d7..0dc8050c2e29 100644
--- a/nixos/modules/services/networking/kresd.nix
+++ b/nixos/modules/services/networking/kresd.nix
@@ -135,8 +135,14 @@ in
 
   ###### implementation
   config = lib.mkIf cfg.enable {
-    assertions = lib.optionals (lib.versions.major cfg.package.version > 5) [
-      "services.kresd only works with knot-resolver 5. Please use services.knot-resolver for knot-resolver 6 and newer."
+    assertions = [
+      {
+        assertion = lib.versionOlder cfg.package.version "6.0.0";
+        message = ''
+          services.kresd only works with knot-resolver 5.
+          Please use services.knot-resolver for knot-resolver 6 and newer.
+        '';
+      }
     ];
     environment = {
       etc."knot-resolver/kresd.conf".source = configFile; # not required