diff --git a/src/ajax/jsonp.js b/src/ajax/jsonp.js
index 5cfb7834a..0af00567c 100644
--- a/src/ajax/jsonp.js
+++ b/src/ajax/jsonp.js
@@ -4,82 +4,81 @@ var jsc = jQuery.now(),
 	jsre = /\=\?(&|$)/,
 	rquery_jsonp = /\?/;
 
-// Default jsonp callback name
-jQuery.ajaxSettings.jsonpCallback = function() {
-	return "jsonp" + jsc++;
-};
+// Default jsonp settings
+jQuery.ajaxSetup({
+	jsonp: "callback",
+	jsonpCallback: function() {
+		return "jsonp" + jsc++;
+	}
+});
 
 // Normalize jsonp queries
 // 1) put callback parameter in url or data
-// 2) sneakily ensure transportDataType is json
-// 3) ensure options jsonp is always provided so that jsonp requests are always
-//    json request with the jsonp option set
-jQuery.ajax.prefilter("json jsonp", function(s) {
+// 2) sneakily ensure transportDataType is always jsonp for jsonp requests
+jQuery.ajax.prefilter("json jsonp", function(s, originalSettings) {
 
-	var transportDataType = s.dataTypes[ 0 ];
+	if ( s.dataTypes[ 0 ] === "jsonp" ||
+		originalSettings.jsonp ||
+		originalSettings.jsonpCallback ||
+		jsre.test(s.url) ||
+		typeof(s.data) === "string" && jsre.test(s.data) ) {
 
-	s.dataTypes[ 0 ] = "json";
-
-	if ( s.jsonp ||
-		transportDataType === "jsonp" ||
-		transportDataType === "json" && ( jsre.test(s.url) || typeof(s.data) === "string" && jsre.test(s.data) ) ) {
-
-		var jsonp = s.jsonp = s.jsonp || "callback",
-			jsonpCallback = s.jsonpCallback =
+		var jsonpCallback = s.jsonpCallback =
 				jQuery.isFunction( s.jsonpCallback ) ? s.jsonpCallback() : s.jsonpCallback,
 			url = s.url.replace(jsre, "=" + jsonpCallback + "$1"),
-			data = s.url == url && typeof(s.data) === "string" ? s.data.replace(jsre, "=" + jsonpCallback + "$1") : s.data;
+			data = s.url === url && typeof(s.data) === "string" ? s.data.replace(jsre, "=" + jsonpCallback + "$1") : s.data;
 
-		if ( url == s.url && data == s.data ) {
-			url = url += (rquery_jsonp.test( url ) ? "&" : "?") + jsonp + "=" + jsonpCallback;
+		if ( url === s.url && data === s.data ) {
+			url += (rquery_jsonp.test( url ) ? "&" : "?") + s.jsonp + "=" + jsonpCallback;
 		}
 
 		s.url = url;
 		s.data = data;
+		s.dataTypes[ 0 ] = "jsonp";
 	}
 
-// Bind transport to json dataType
-}).transport("json", function(s) {
+// Bind transport to jsonp dataType
+}).transport("jsonp", function(s) {
 
-	if ( s.jsonp ) {
+	// Put callback in place
+	var responseContainer,
+		jsonpCallback = s.jsonpCallback,
+		previous = window[ jsonpCallback ];
 
-		// Put callback in place
-		var responseContainer,
-			jsonpCallback = s.jsonpCallback,
-			previous = window[ jsonpCallback ];
+	window [ jsonpCallback ] = function( response ) {
+		responseContainer = [response];
+	};
 
-		window [ jsonpCallback ] = function( response ) {
-			responseContainer = [response];
-		};
+	s.complete = [function() {
 
-		s.complete = [function() {
+		// Set callback back to previous value
+		window[ jsonpCallback ] = previous;
 
-			// Set callback back to previous value
-			window[ jsonpCallback ] = previous;
-
-			// Call if it was a function and we have a response
-			if ( previous) {
-				if ( responseContainer && jQuery.isFunction ( previous ) ) {
-					window[ jsonpCallback ] ( responseContainer[0] );
-				}
-			} else {
-				// else, more memory leak avoidance
-				try{ delete window[ jsonpCallback ]; } catch(e){}
+		// Call if it was a function and we have a response
+		if ( previous) {
+			if ( responseContainer && jQuery.isFunction ( previous ) ) {
+				window[ jsonpCallback ] ( responseContainer[0] );
 			}
+		} else {
+			// else, more memory leak avoidance
+			try{ delete window[ jsonpCallback ]; } catch(e){}
+		}
 
-		}, s.complete ];
+	}, s.complete ];
 
-		// Use data converter to retrieve json after script execution
-		s.converters["script json"] = function() {
-			if ( ! responseContainer ) {
-				jQuery.error( jsonpCallback + " was not called" );
-			}
-			return responseContainer[ 0 ];
-		};
+	// Sneakily ensure this will be handled as json
+	s.dataTypes[ 0 ] = "json";
 
-		// Delegate to script transport
-		return "script";
-	}
+	// Use data converter to retrieve json after script execution
+	s.converters["script json"] = function() {
+		if ( ! responseContainer ) {
+			jQuery.error( jsonpCallback + " was not called" );
+		}
+		return responseContainer[ 0 ];
+	};
+
+	// Delegate to script transport
+	return "script";
 });
 
 })( jQuery );