diff --git a/dom/security/test/csp/file_data_csp_inheritance.html b/dom/security/test/csp/file_data_csp_inheritance.html
index 299c30255aa6..cbb4865343db 100644
--- a/dom/security/test/csp/file_data_csp_inheritance.html
+++ b/dom/security/test/csp/file_data_csp_inheritance.html
@@ -13,8 +13,10 @@
   var frame = document.getElementById("dataFrame");
   var principal = SpecialPowers.wrap(frame.contentDocument).nodePrincipal;
   var cspJSON = principal.cspJSON;
-  var result = principal.cspJSON ? "dataInheritsCSP" : "dataDoesNotInheritCSP";
-  window.parent.postMessage({result}, "*");
+  var cspOBJ = JSON.parse(principal.cspJSON);
+  // make sure we got >>one<< policy
+  var policies = cspOBJ["csp-policies"];
+  window.parent.postMessage({result: policies.length}, "*");
 </script>
 
 </body>
diff --git a/dom/security/test/csp/test_data_csp_inheritance.html b/dom/security/test/csp/test_data_csp_inheritance.html
index 3afc4f7c02bc..bde2f5617e65 100644
--- a/dom/security/test/csp/test_data_csp_inheritance.html
+++ b/dom/security/test/csp/test_data_csp_inheritance.html
@@ -22,7 +22,9 @@ SimpleTest.waitForExplicitFinish();
 window.addEventListener("message", receiveMessage);
 function receiveMessage(event) {
   window.removeEventListener("message", receiveMessage);
-  is(event.data.result, "dataInheritsCSP",
+  // toplevel CSP should apply to data: URI iframe hence resulting
+  // in 1 applied policy.
+  is(event.data.result, 1,
      "data: URI iframe inherits CSP from including context");
   SimpleTest.finish();
 }