diff --git a/src/scripts/utils.js b/src/scripts/utils.js
index adf3314..778226d 100644
--- a/src/scripts/utils.js
+++ b/src/scripts/utils.js
@@ -1,3 +1,4 @@
+import { DockerRegistryUIError } from './error.js';
 const LOCAL_STORAGE_KEY = 'registryServer';
 
 export function bytesToSize(bytes) {
@@ -221,21 +222,25 @@ export function stringToArray(value) {
   return value && typeof value === 'string' ? value.split(',') : [];
 }
 
+const TAGLIST_ORDER_REGEX = /(alpha-(asc|desc);num-(asc|desc))|(num-(asc|desc);alpha-(asc|desc))/;
+
 export const taglistOrderVariants = (taglistOrder) => {
   switch (taglistOrder) {
     case 'desc':
-    case 'alpha-desc':
       return 'alpha-desc;num-desc';
     case 'asc':
-    case 'num-asc':
       return 'num-asc;alpha-asc';
+    case 'alpha-desc':
+    case 'alpha-asc':
+    case 'num-desc':
+    case 'num-asc':
+      return `${taglistOrder};${taglistOrder.startsWith('num') ? 'alpha' : 'num'}-asc`;
     default:
       if (!taglistOrder) {
         return 'num-asc;alpha-asc';
-      } else if (taglistOrder.indexOf(';') === -1) {
-        return taglistOrder.startsWith('num-') ? `${taglistOrder};alpha-asc` : `${taglistOrder};num-asc`;
-      } else {
+      } else if (TAGLIST_ORDER_REGEX.test(taglistOrder)) {
         return taglistOrder;
       }
+      throw new DockerRegistryUIError(`The order \`${taglistOrder}\` is not recognized.`);
   }
 };
diff --git a/test/utils.test.js b/test/utils.test.js
index 8ff84d1..c87c8d3 100644
--- a/test/utils.test.js
+++ b/test/utils.test.js
@@ -1,33 +1,37 @@
 import { taglistOrderVariants } from '../src/scripts/utils.js';
+import { DockerRegistryUIError } from '../src/scripts/error.js';
 import assert from 'assert';
 
 describe('utils tests', () => {
   describe('taglistOrderVariants', () => {
     it(`should return the input when it's well formed and num first`, () => {
       const expected = ['num-asc;alpha-asc', 'num-asc;alpha-desc', 'num-desc;alpha-asc', 'num-desc;alpha-asc'];
-      expected.forEach(
-        (e) => assert.deepEqual(taglistOrderVariants(e), e)
-      );
+      expected.forEach((e) => assert.deepEqual(taglistOrderVariants(e), e));
     });
 
     it(`should return the input when it's well formed and alpha first`, () => {
       const expected = ['alpha-asc;num-asc', 'alpha-asc;num-desc', 'alpha-desc;num-asc', 'alpha-desc;num-asc'];
-      expected.forEach(
-        (e) => assert.deepEqual(taglistOrderVariants(e), e)
-      );
+      expected.forEach((e) => assert.deepEqual(taglistOrderVariants(e), e));
     });
 
     it('should return correct variant of `num-asc;alpha-asc`', () => {
       const expected = 'num-asc;alpha-asc';
-      ['asc', 'num-asc'].forEach(
-        (e) => assert.deepEqual(taglistOrderVariants(e), expected)
-      );
+      [undefined, '', 'asc', 'num-asc'].forEach((e) => assert.deepEqual(taglistOrderVariants(e), expected));
     });
 
     it('should return correct variant of `alpha-desc;num-desc`', () => {
       const expected = 'alpha-desc;num-desc';
-      ['desc', 'alpha-desc'].forEach(
-        (e) => assert.deepEqual(taglistOrderVariants(e), expected)
+      ['desc'].forEach((e) => assert.deepEqual(taglistOrderVariants(e), expected));
+    });
+
+    it('should extend correctly orders', () => {
+      ['alpha-desc', 'alpha-asc'].forEach((e) => assert.deepEqual(taglistOrderVariants(e), `${e};num-asc`));
+      ['num-desc', 'num-asc'].forEach((e) => assert.deepEqual(taglistOrderVariants(e), `${e};alpha-asc`));
+    });
+
+    it('should throw error on incorrect values', () => {
+      ['alpha-desc;alpha-asc', 'foobar'].forEach((e) =>
+        assert.throws(() => taglistOrderVariants(e), DockerRegistryUIError, `Did not throw on ${e}`)
       );
     });
   });