diff --git a/src/ajax.js b/src/ajax.js
index 394c84e66..3f71f8c6e 100644
--- a/src/ajax.js
+++ b/src/ajax.js
@@ -247,6 +247,7 @@ jQuery.extend({
 			target = jQuery.ajaxSettings;
 		}
 		ajaxExtend( target, settings );
+
 		return target;
 	},
 
@@ -557,8 +558,9 @@ jQuery.extend({
 
 		// Remove hash character (#7531: and string promotion)
 		// Add protocol if not provided (#5866: IE7 issue with protocol-less urls)
+		// Handle falsy url in the settings object (#10093: consistency with old signature)
 		// We also use the url parameter if available
-		s.url = ( ( url || s.url ) + "" ).replace( rhash, "" ).replace( rprotocol, ajaxLocParts[ 1 ] + "//" );
+		s.url = ( ( url || s.url || ajaxLocation ) + "" ).replace( rhash, "" ).replace( rprotocol, ajaxLocParts[ 1 ] + "//" );
 
 		// Extract dataTypes list
 		s.dataTypes = jQuery.trim( s.dataType || "*" ).toLowerCase().split( core_rspace );
diff --git a/test/unit/ajax.js b/test/unit/ajax.js
index d11cb13f7..4a93c65fe 100644
--- a/test/unit/ajax.js
+++ b/test/unit/ajax.js
@@ -1451,7 +1451,7 @@ if ( jQuery.ajax && ( !isLocal || hasPHP ) ) {
 
 
 	jQuery.each( [ "Same Domain", "Cross Domain" ], function( crossDomain, label ) {
-	
+
 		asyncTest( "jQuery.ajax() - JSONP, Query String (?n)" + label, function() {
 			expect( 4 );
 
@@ -1543,7 +1543,7 @@ if ( jQuery.ajax && ( !isLocal || hasPHP ) ) {
 					plus();
 				}
 			});
-			
+
 			window["jsonpResults"] = function( data ) {
 				ok( data["data"], "JSON results returned (GET, custom callback function)" );
 				window["jsonpResults"] = undefined;
@@ -2725,4 +2725,38 @@ if ( jQuery.ajax && ( !isLocal || hasPHP ) ) {
 		expect( 1 );
 		ok( jQuery.active === 0, "ajax active counter should be zero: " + jQuery.active );
 	});
+
+	test("jQuery.ajax - falsy url as argument (#10093)", function() {
+		expect( 4 );
+
+		jQuery.ajaxSetup({ timeout: 0 });
+
+		stop();
+
+		jQuery.when(
+			jQuery.ajax("").success(function(){ ok( true, "settings object - empty string" ); }),
+			jQuery.ajax( false ).success(function(){ ok( true, "false" ); }),
+			jQuery.ajax( null ).success(function(){ ok( true, "null" ); }),
+			jQuery.ajax( undefined ).success(function(){ ok( true, "undefined" ); })
+		).always(function () {
+			start();
+		});
+	});
+
+	test("jQuery.ajax - falsy url in settings object (#10093)", function() {
+		expect( 4 );
+
+		jQuery.ajaxSetup({ timeout: 0 });
+
+		stop();
+
+		jQuery.when(
+			jQuery.ajax({ url: "" }).success(function(){ ok( true, "settings object - empty string" ); }),
+			jQuery.ajax({ url: false }).success(function(){ ok( true, "false" ); }),
+			jQuery.ajax({ url: null }).success(function(){ ok( true, "null" ); }),
+			jQuery.ajax({ url: undefined }).success(function(){ ok( true, "undefined" ); })
+		).always(function () {
+			start();
+		});
+	});
 }