diff --git a/ElasticSearchLambda/ZombieWorkshopSearchIndexing.js b/ElasticSearchLambda/ZombieWorkshopSearchIndexing.js
index 9bf7442..5112da4 100644
--- a/ElasticSearchLambda/ZombieWorkshopSearchIndexing.js
+++ b/ElasticSearchLambda/ZombieWorkshopSearchIndexing.js
@@ -47,6 +47,7 @@ function postToES(doc, context) {
     req.path = path.join('/', esDomain.index, esDomain.doctype);
     req.region = esDomain.region;
     req.headers['presigned-expires'] = false;
+    req.headers['Content-Type'] = 'application/json';
     req.headers['Host'] = endpoint.host;
     req.body = doc;