diff --git a/src/package.ts b/src/package.ts
index ced035b..c8f63f4 100644
--- a/src/package.ts
+++ b/src/package.ts
@@ -140,6 +140,14 @@ export class TagsProcessor extends BaseProcessor {
 				keywords = [...keywords, 'theme'];
 			}
 
+			const activationEvents = this.manifest.activationEvents || [];
+			const languages = activationEvents
+				.map(e => /^onLanguage:(.*)$/.exec(e))
+				.filter(r => !!r)
+				.map(r => r[1]);
+
+			keywords = [...keywords, ...languages];
+
 			this.vsix.tags = _.unique(keywords).join(',');
 		});
 	}
diff --git a/src/test/package.test.ts b/src/test/package.test.ts
index c3ea8fe..0fbc54f 100644
--- a/src/test/package.test.ts
+++ b/src/test/package.test.ts
@@ -441,7 +441,7 @@ describe('toVsixManifest', () => {
 
 		return _toVsixManifest(manifest, [])
 			.then(parseXml)
-			.then(result => assert.deepEqual(result.PackageManifest.Metadata[0].Tags, ['theme']));
+			.then(result => assert.deepEqual(result.PackageManifest.Metadata[0].Tags[0], 'theme'));
 	});
 
 	it('should not automatically add theme tag when themes are empty', () => {
@@ -457,7 +457,21 @@ describe('toVsixManifest', () => {
 
 		return _toVsixManifest(manifest, [])
 			.then(parseXml)
-			.then(result => assert.deepEqual(result.PackageManifest.Metadata[0].Tags, ['']));
+			.then(result => assert.deepEqual(result.PackageManifest.Metadata[0].Tags[0], ''));
+	});
+
+	it('should automatically add language tag', () => {
+		const manifest = {
+			name: 'test',
+			publisher: 'mocha',
+			version: '0.0.1',
+			engines: Object.create(null),
+			activationEvents: ['onLanguage:go']
+		};
+
+		return _toVsixManifest(manifest, [])
+			.then(parseXml)
+			.then(result => assert.deepEqual(result.PackageManifest.Metadata[0].Tags[0], 'go'));
 	});
 
 	it('should remove duplicate tags', () => {
@@ -471,7 +485,7 @@ describe('toVsixManifest', () => {
 
 		return _toVsixManifest(manifest, [])
 			.then(parseXml)
-			.then(result => assert.deepEqual(result.PackageManifest.Metadata[0].Tags, ['theme']));
+			.then(result => assert.deepEqual(result.PackageManifest.Metadata[0].Tags[0], 'theme'));
 	});
 });