diff --git a/servant-js/src/Servant/JS/Vanilla.hs b/servant-js/src/Servant/JS/Vanilla.hs
index 7313f540..89ef91d5 100644
--- a/servant-js/src/Servant/JS/Vanilla.hs
+++ b/servant-js/src/Servant/JS/Vanilla.hs
@@ -33,6 +33,7 @@ generateVanillaJSWith opts req = "\n" <>
  <> "  var xhr = new XMLHttpRequest();\n"
  <> "  xhr.open('" <> method <> "', " <> url <> ", true);\n"
  <>    reqheaders
+ <> "  xhr.setRequestHeader(\"Accept\",\"application/json\");\n"
  <> "  xhr.onreadystatechange = function (e) {\n"
  <> "    if (xhr.readyState == 4) {\n"
  <> "        var value = JSON.parse(xhr.responseText);\n"