diff --git a/bootstrap-number-input.js b/bootstrap-number-input.js
index b1c7159..6fee528 100644
--- a/bootstrap-number-input.js
+++ b/bootstrap-number-input.js
@@ -27,6 +27,8 @@
 		var settings = $.extend({
 			upClass: 'default',
 			downClass: 'default',
+			upText: '+',
+			downText: '-',
 			center: true
 			}, options );
 
@@ -36,45 +38,47 @@
 
 			var min = self.attr('min');
 			var max = self.attr('max');
+			var step = parseInt(self.attr('step')) || 1;
 
 			function setText(n) {
-				if((min && n < min) || (max && n > max)) {
+				if (isNaN(n) || (min && n < min) || (max && n > max)) {
 					return false;
 				}
 
 				clone.focus().val(n);
+				clone.trigger('change');
 				return true;
 			}
 
 			var group = $("<div class='input-group'></div>");
-			var down = $("<button type='button'>-</button>").attr('class', 'btn btn-' + settings.downClass).click(function() {
-				setText(parseInt(clone.val()) - 1);
+			var down = $("<button type='button'>" + settings.downText + "</button>").attr('class', 'btn btn-' + settings.downClass).click(function() {
+				setText(parseInt(clone.val() || clone.attr('value')) - step);
 			});
-			var up = $("<button type='button'>+</button>").attr('class', 'btn btn-' + settings.upClass).click(function() {
-				setText(parseInt(clone.val()) + 1);
+			var up = $("<button type='button'>" + settings.upText + "</button>").attr('class', 'btn btn-' + settings.upClass).click(function() {
+				setText(parseInt(clone.val() || clone.attr('value')) + step);
 			});
 			$("<span class='input-group-btn'></span>").append(down).appendTo(group);
 			clone.appendTo(group);
-			if(clone) {
+			if(clone && settings.center) {
 				clone.css('text-align', 'center');
 			}
 			$("<span class='input-group-btn'></span>").append(up).appendTo(group);
 
 			// remove spins from original
-			clone.prop('type', 'text').keydown(function (e) {
+			clone.prop('type', 'text').keydown(function(e) {
 				if ($.inArray(e.keyCode, [46, 8, 9, 27, 13, 110, 190]) !== -1 ||
-					(e.keyCode == 65 && e.ctrlKey === true) || 
+					(e.keyCode == 65 && e.ctrlKey === true) ||
 					(e.keyCode >= 35 && e.keyCode <= 39)) {
 					return;
 				}
-				if ((e.shiftKey || (e.keyCode < 48 || e.keyCode > 57)) && (e.keyCode < 96 || e.keyCode > 105)) {				
+				if ((e.shiftKey || (e.keyCode < 48 || e.keyCode > 57)) && (e.keyCode < 96 || e.keyCode > 105)) {
 					e.preventDefault();
 				}
 
 				var c = String.fromCharCode(e.which);
 				var n = parseInt(clone.val() + c);
 
-				if((min && n < min) || (max && n > max)) {
+				if ((min && n < min) || (max && n > max)) {
 					e.preventDefault();
 				}
 			});
@@ -83,4 +87,3 @@
 		});
 	};
 } ( jQuery ));
-