diff --git a/dom/apps/src/AppsUtils.jsm b/dom/apps/src/AppsUtils.jsm
index 3e1b6a62119f..59d2527f5f3a 100644
--- a/dom/apps/src/AppsUtils.jsm
+++ b/dom/apps/src/AppsUtils.jsm
@@ -184,14 +184,6 @@ this.AppsUtils = {
     return true;
   },
 
-  checkManifestContentType(installOrigin, webappOrigin, contentType) {
-    if (installOrigin != webappOrigin && contentType != "application/x-web-app-manifest+json") {
-      return false;
-    }
-
-    return true;
-  },
-
   /**
    * Determines whether the manifest allows installs for the given origin.
    * @param object aManifest
diff --git a/dom/apps/src/Webapps.js b/dom/apps/src/Webapps.js
index 68d8d8b80f6c..0e0b9f9c0908 100644
--- a/dom/apps/src/Webapps.js
+++ b/dom/apps/src/Webapps.js
@@ -105,11 +105,6 @@ WebappsRegistry.prototype = {
 
     xhr.addEventListener("load", (function() {
       if (xhr.status == 200) {
-        if (!AppsUtils.checkManifestContentType(installOrigin, this._getOrigin(aURL), xhr.getResponseHeader("content-type"))) {
-          Services.DOMRequest.fireError(request, "INVALID_MANIFEST");
-          return;
-        }
-
         let manifest;
         try {
           manifest = JSON.parse(xhr.responseText, installOrigin);
@@ -219,11 +214,6 @@ WebappsRegistry.prototype = {
 
     xhr.addEventListener("load", (function() {
       if (xhr.status == 200) {
-        if (!AppsUtils.checkManifestContentType(installOrigin, this._getOrigin(aURL), xhr.getResponseHeader("content-type"))) {
-          Services.DOMRequest.fireError(request, "INVALID_MANIFEST");
-          return;
-        }
-
         let manifest;
         try {
           manifest = JSON.parse(xhr.responseText, installOrigin);
diff --git a/dom/tests/mochitest/webapps/test_install_errors.xul b/dom/tests/mochitest/webapps/test_install_errors.xul
index 2d436433afbd..2f50e4f83a5d 100644
--- a/dom/tests/mochitest/webapps/test_install_errors.xul
+++ b/dom/tests/mochitest/webapps/test_install_errors.xul
@@ -97,7 +97,7 @@ function invalidContent(next) {
   };
 
   request.onsuccess = function onInstall() {
-    ok(false, "manifest with bad content type should fail");
+    todo(false, "manifest with bad content type fails");
     this.result.uninstall().onsuccess = function onUninstall() {
       next();
     };