diff --git a/src/model/image-tag.test.ts b/src/model/image-tag.test.ts
index 56283fa..806dec4 100644
--- a/src/model/image-tag.test.ts
+++ b/src/model/image-tag.test.ts
@@ -8,9 +8,13 @@ describe('ImageTag', () => {
       expect(() => new ImageTag(unityVersion)).not.toThrow();
     });
 
-    test.each(['2000.0.0f0', '2011.1.11f1'])('accepts %p version format', (version) => {
+    test.each(['2000.0.0f0', '2011.1.11f1', '6000.0.0f0'])('accepts %p version format', (version) => {
       expect(() => new ImageTag(version)).not.toThrow();
     });
+
+    test.each(['1999.1.1f1', '6000.1.invalid'])('rejects %p version format', (version) => {
+      expect(() => new ImageTag(version)).toThrow(`Invalid version "${version}".`);
+    });
   });
   describe('toString', () => {
     it('returns the correct version', () => {
diff --git a/src/model/image-tag.ts b/src/model/image-tag.ts
index 2fe8fdf..fd92a06 100644
--- a/src/model/image-tag.ts
+++ b/src/model/image-tag.ts
@@ -27,7 +27,7 @@ class ImageTag {
   }
 
   static get versionPattern() {
-    return /^20\d{2}\.\d\.\w{3,4}|3$/;
+    return /^(20\d{2}\.\d\.\w{3,4}|6000\.\d\.\w{3,4})$/;
   }
 
   static get imageSuffixes() {