diff --git a/packages/cli/src/metadataGeneration/extension.ts b/packages/cli/src/metadataGeneration/extension.ts
index 08ee2ffc4..69c43be27 100644
--- a/packages/cli/src/metadataGeneration/extension.ts
+++ b/packages/cli/src/metadataGeneration/extension.ts
@@ -12,11 +12,15 @@ export function getExtensions(decorators: ts.Identifier[], metadataGenerator: Me
 
     const [decoratorKeyArg, decoratorValueArg] = extensionDecorator.parent.arguments;
 
-    if (!ts.isStringLiteral(decoratorKeyArg)) {
+    if (!ts.isStringLiteral(decoratorKeyArg) && !ts.isIdentifier(decoratorKeyArg)) {
       throw new Error('The first argument of @Extension must be a string');
     }
 
-    const attributeKey = decoratorKeyArg.text;
+    const attributeKey = ts.isIdentifier(decoratorKeyArg) ? getInitializerValue(decoratorKeyArg, metadataGenerator.typeChecker) : decoratorKeyArg.text;
+
+    if (typeof attributeKey !== 'string') {
+      throw new Error('The first argument of @Extension must be a string');
+    }
 
     if (!decoratorValueArg) {
       throw new Error(`Extension '${attributeKey}' must contain a value`);
diff --git a/tests/fixtures/controllers/methodController.ts b/tests/fixtures/controllers/methodController.ts
index 2989c06dd..5c668d275 100644
--- a/tests/fixtures/controllers/methodController.ts
+++ b/tests/fixtures/controllers/methodController.ts
@@ -27,6 +27,8 @@ const TEST_SEC = {
   secondSec: [TEST_ENUM.ADMIN, TEST_ENUM.OWNER],
 };
 
+const ATT_KEY9 = 'x-attKey9';
+
 @Route('MethodTest')
 export class MethodController extends Controller {
   @Options('Options')
@@ -165,6 +167,7 @@ export class MethodController extends Controller {
   @Extension('x-attKey6', [{ y0: 'yt0', y1: 'yt1', y2: 123, y3: true, y4: null }, { y2: 'yt2' }])
   @Extension('x-attKey7', { test: ['testVal', 123, true, null] })
   @Extension('x-attKey8', { test: { testArray: ['testVal1', true, null, ['testVal2', 'testVal3', 123, true, null]] } })
+  @Extension(ATT_KEY9, 'identifierAttValue')
   @Get('Extension')
   public async extension(): Promise<TestModel> {
     return new ModelService().getModel();
diff --git a/tests/unit/swagger/definitionsGeneration/metadata.spec.ts b/tests/unit/swagger/definitionsGeneration/metadata.spec.ts
index 85b75aa0b..4cc5097d6 100644
--- a/tests/unit/swagger/definitionsGeneration/metadata.spec.ts
+++ b/tests/unit/swagger/definitionsGeneration/metadata.spec.ts
@@ -166,10 +166,13 @@ describe('Metadata generation', () => {
 
       expect(method.responses.length).to.equal(5);
 
-      const badResponse = method.responses[1]
+      const badResponse = method.responses[1];
       expect(badResponse.name).to.equal('400');
       expect(badResponse.description).to.equal('Bad Request');
-      expect(badResponse.examples).to.deep.equal([{ status: 400, message: 'reason 1' }, { status: 400, message: 'reason 2' }]);
+      expect(badResponse.examples).to.deep.equal([
+        { status: 400, message: 'reason 1' },
+        { status: 400, message: 'reason 2' },
+      ]);
 
       const unauthResponse = method.responses[2];
       expect(unauthResponse.name).to.equal('401');
@@ -316,6 +319,7 @@ describe('Metadata generation', () => {
         { key: 'x-attKey6', value: [{ y0: 'yt0', y1: 'yt1', y2: 123, y3: true, y4: null }, { y2: 'yt2' }] },
         { key: 'x-attKey7', value: { test: ['testVal', 123, true, null] } },
         { key: 'x-attKey8', value: { test: { testArray: ['testVal1', true, null, ['testVal2', 'testVal3', 123, true, null]] } } },
+        { key: 'x-attKey9', value: 'identifierAttValue' },
       ];
 
       expect(method.extensions).to.deep.equal(expectedExtensions);