diff --git a/axios/axios-tests.ts b/axios/axios-tests.ts
index a321e97f19..eb98e2710c 100644
--- a/axios/axios-tests.ts
+++ b/axios/axios-tests.ts
@@ -80,7 +80,11 @@ var axiosInstance = axios.create({
     timeout: 1000
 });
 
-axiosInstance.request({url: "issues/1"});
+axiosInstance.request({url: "issues/1"}).then(res => {
+    if (res.headers['content-type'].startsWith('application/json')) {
+        throw new Error('Unexpected content-type');
+    }
+});
 
 axios.all<Repository, Repository>([getRepoDetails, getRepoDetails]).then(([repo1, repo2]) => {
     var sumIds = repo1.data.id + repo2.data.id;
diff --git a/axios/index.d.ts b/axios/index.d.ts
index a2c5bfbd45..d66dc3d48c 100644
--- a/axios/index.d.ts
+++ b/axios/index.d.ts
@@ -159,7 +159,7 @@ declare namespace Axios {
         /**
          * headers that the server responded with
          */
-        headers: Object;
+        headers: {[index: string]: any};
 
         /**
          * config that was provided to `axios` for the request