diff --git a/src/ajax/xhr.js b/src/ajax/xhr.js
index a24feaf1a0..4c44e857c7 100644
--- a/src/ajax/xhr.js
+++ b/src/ajax/xhr.js
@@ -99,7 +99,7 @@ if ( jQuery.support.ajax ) {
 					// Do send the request
 					// This may raise an exception which is actually
 					// handled in jQuery.ajax (so no try/catch here)
-					xhr.send( ( s.hasContent && s.data ) || null );
+					xhr.send( ( s.hasContent && s.data ) || {} );
 
 					// Listener
 					callback = function( _, isAbort ) {