diff --git a/test/middleware-mockserver.js b/test/middleware-mockserver.js
index 863aaf6bd..165d33187 100644
--- a/test/middleware-mockserver.js
+++ b/test/middleware-mockserver.js
@@ -62,7 +62,7 @@ var mocks = {
 	script: function( req, resp ) {
 		if ( req.query.header === "ecma" ) {
 			resp.writeHead( 200, { "content-type": "application/ecmascript" } );
-		} else if ( req.query.header ) {
+		} else if ( "header" in req.query ) {
 			resp.writeHead( 200, { "content-type": "text/javascript" } );
 		} else {
 			resp.writeHead( 200, { "content-type": "text/html" } );
diff --git a/test/unit/ajax.js b/test/unit/ajax.js
index b3b78cc5f..271496ce1 100644
--- a/test/unit/ajax.js
+++ b/test/unit/ajax.js
@@ -118,7 +118,7 @@ QUnit.module( "ajax", {
 		return {
 			create: function( options ) {
 				options.crossDomain = true;
-				return jQuery.ajax( url( "mock.php?action=script" ), options );
+				return jQuery.ajax( url( "mock.php?action=script&header" ), options );
 			},
 			success: function() {
 				assert.ok( true, "success" );