diff --git a/packages/cli/src/metadataGeneration/typeResolver.ts b/packages/cli/src/metadataGeneration/typeResolver.ts
index bbd40248..57c2ad5f 100644
--- a/packages/cli/src/metadataGeneration/typeResolver.ts
+++ b/packages/cli/src/metadataGeneration/typeResolver.ts
@@ -596,6 +596,9 @@ export class TypeResolver {
       const isGlobalDeclaration = (mod: ts.ModuleDeclaration) => mod.name.kind === ts.SyntaxKind.Identifier && mod.name.text === 'global';
 
       while (!ts.isSourceFile(actNode)) {
+        if (ts.isBlock(actNode)) {
+          break;
+        }
         if (!(isFirst && ts.isEnumDeclaration(actNode)) && !ts.isModuleBlock(actNode)) {
           throwUnless(ts.isModuleDeclaration(actNode), new GenerateMetadataError(`This node kind is unknown: ${actNode.kind}`, type));
 
diff --git a/tests/fixtures/controllers/getController.ts b/tests/fixtures/controllers/getController.ts
index 68d23ef1..3730ddf3 100644
--- a/tests/fixtures/controllers/getController.ts
+++ b/tests/fixtures/controllers/getController.ts
@@ -107,6 +107,14 @@ export class GetTestController extends Controller {
     return {} as GetterInterfaceHerited;
   }
 
+  @Get('InnerInterface')
+  public async getInnerInterface() {
+    interface InnerInterface {
+      value?: string;
+    }
+    return { value: 'test' } as InnerInterface;
+  }
+
   @Get('ModuleRedeclarationAndNamespace')
   public async getModuleRedeclarationAndNamespace(): Promise<TsoaTest.TestModel73> {
     return {} as TsoaTest.TestModel73;
diff --git a/tests/unit/swagger/schemaDetails3.spec.ts b/tests/unit/swagger/schemaDetails3.spec.ts
index 20b92681..ff0c1e6f 100644
--- a/tests/unit/swagger/schemaDetails3.spec.ts
+++ b/tests/unit/swagger/schemaDetails3.spec.ts
@@ -4647,6 +4647,28 @@ describe('Definition generation for OpenAPI 3.0.0', () => {
     expect(extensionPath['x-attKey8']).to.deep.equal({ test: { testArray: ['testVal1', true, null, ['testVal2', 'testVal3', 123, true, null]] } });
   });
 
+  describe('Inner interface', () => {
+    it('should generate the proper schema', () => {
+      const ref = specDefault.spec.paths['/GetTest/InnerInterface'].get?.responses['200'].content?.['application/json']['schema']?.['$ref'];
+      expect(ref).to.equal('#/components/schemas/InnerInterface');
+      expect(getComponentSchema('InnerInterface', specDefault)).to.deep.equal({
+        additionalProperties: true,
+        description: undefined,
+        properties: {
+          value: {
+            default: undefined,
+            description: undefined,
+            example: undefined,
+            format: undefined,
+            type: 'string',
+          },
+        },
+        required: undefined,
+        type: 'object',
+      });
+    });
+  });
+
   describe('module declarations with namespaces', () => {
     it('should generate the proper schema for a model declared in a namespace in a module', () => {
       /* tslint:disable:no-string-literal */