diff --git a/src/adapters/aws/api-gateway-v1.adapter.ts b/src/adapters/aws/api-gateway-v1.adapter.ts
index 5cd35665..0af4dde8 100644
--- a/src/adapters/aws/api-gateway-v1.adapter.ts
+++ b/src/adapters/aws/api-gateway-v1.adapter.ts
@@ -11,6 +11,7 @@ import {
 import {
   getDefaultIfUndefined,
   getEventBodyAsBuffer,
+  getFlattenedHeadersMap,
   getMultiValueHeadersMap,
   getPathWithQueryStringParams,
 } from '../../core';
@@ -87,8 +88,8 @@ export class ApiGatewayV1Adapter
       partialEventV1.version !== '2.0' &&
       partialEventV1.headers &&
       partialEventV1.multiValueHeaders &&
-      (partialEventV1.queryStringParameters ===
-        partialEventV1.multiValueQueryStringParameters ||
+      ((partialEventV1.queryStringParameters === null &&
+        partialEventV1.multiValueQueryStringParameters === null) ||
         (partialEventV1.queryStringParameters &&
           partialEventV1.multiValueQueryStringParameters))
     );
@@ -99,7 +100,7 @@ export class ApiGatewayV1Adapter
    */
   public getRequest(event: APIGatewayProxyEvent): AdapterRequest {
     const method = event.httpMethod;
-    const headers = event.headers;
+    const headers = getFlattenedHeadersMap(event.headers, ',', true);
     const path = this.getPathFromEvent(event);
 
     let body: Buffer | undefined;
diff --git a/test/adapters/aws/api-gateway-v1.adapter.spec.ts b/test/adapters/aws/api-gateway-v1.adapter.spec.ts
index 021d2edf..b47e3099 100644
--- a/test/adapters/aws/api-gateway-v1.adapter.spec.ts
+++ b/test/adapters/aws/api-gateway-v1.adapter.spec.ts
@@ -42,6 +42,8 @@ describe(ApiGatewayV1Adapter.name, () => {
 
       expect(result).toHaveProperty('method', method);
       expect(result).toHaveProperty('headers');
+      expect(result.headers).not.toHaveProperty('Accept');
+      expect(result.headers).toHaveProperty('accept');
 
       expect(result).toHaveProperty('body');
       expect(result.body).toBeInstanceOf(Buffer);