diff --git a/src/Calendar.js b/src/Calendar.js
index 2a544bb..626e28c 100644
--- a/src/Calendar.js
+++ b/src/Calendar.js
@@ -641,13 +641,13 @@ function Calendar(element, instanceOptions) {
 	
 	
 	function prevYear() {
-		date.add('years', -1);
+		date.add(-1, 'years');
 		renderView();
 	}
 	
 	
 	function nextYear() {
-		date.add('years', 1);
+		date.add(1, 'years');
 		renderView();
 	}
 	
diff --git a/src/agenda/AgendaDayView.js b/src/agenda/AgendaDayView.js
index fdbaf8f..ab1877a 100644
--- a/src/agenda/AgendaDayView.js
+++ b/src/agenda/AgendaDayView.js
@@ -15,7 +15,7 @@ function AgendaDayView(element, calendar) { // TODO: make a DayView mixin
 
 
 	function incrementDate(date, delta) {
-		var out = date.clone().stripTime().add('days', delta);
+		var out = date.clone().stripTime().add(delta, 'days');
 		out = t.skipHiddenDays(out, delta < 0 ? -1 : 1);
 		return out;
 	}
@@ -24,7 +24,7 @@ function AgendaDayView(element, calendar) { // TODO: make a DayView mixin
 	function render(date) {
 
 		t.start = t.intervalStart = date.clone().stripTime();
-		t.end = t.intervalEnd = t.start.clone().add('days', 1);
+		t.end = t.intervalEnd = t.start.clone().add(1, 'days');
 
 		t.title = calendar.formatDate(t.start, t.opt('titleFormat'));
 
diff --git a/src/agenda/AgendaEventRenderer.js b/src/agenda/AgendaEventRenderer.js
index 5649290..428156c 100644
--- a/src/agenda/AgendaEventRenderer.js
+++ b/src/agenda/AgendaEventRenderer.js
@@ -423,8 +423,8 @@ function AgendaEventRenderer() {
 						if (!cell.row) { // on full-days
 							
 							renderDayOverlay(
-								event.start.clone().add('days', dayDelta),
-								getEventEnd(event).add('days', dayDelta)
+								event.start.clone().add(dayDelta, 'days'),
+								getEventEnd(event).add(dayDelta, 'days')
 							);
 
 							resetElement();
@@ -469,7 +469,7 @@ function AgendaEventRenderer() {
 				}
 				else { // changed!
 
-					var eventStart = event.start.clone().add('days', dayDelta); // already assumed to have a stripped time
+					var eventStart = event.start.clone().add(dayDelta, 'days'); // already assumed to have a stripped time
 					var snapTime;
 					var snapIndex;
 					if (!allDay) {
@@ -589,12 +589,12 @@ function AgendaEventRenderer() {
 
 					// compute new dates
 					if (isAllDay) {
-						eventStart = event.start.clone().stripTime().add('days', dayDelta);
+						eventStart = event.start.clone().stripTime().add(dayDelta, 'days');
 						eventEnd = eventStart.clone().add(calendar.defaultAllDayEventDuration);
 					}
 					else {
-						eventStart = event.start.clone().add(snapDelta * snapDuration).add('days', dayDelta);
-						eventEnd = getEventEnd(event).add(snapDelta * snapDuration).add('days', dayDelta);
+						eventStart = event.start.clone().add(snapDelta * snapDuration).add(dayDelta, 'days');
+						eventEnd = getEventEnd(event).add(snapDelta * snapDuration).add(dayDelta, 'days');
 					}
 
 					updateUI();
diff --git a/src/agenda/AgendaView.js b/src/agenda/AgendaView.js
index 8a73c27..61f60f7 100644
--- a/src/agenda/AgendaView.js
+++ b/src/agenda/AgendaView.js
@@ -636,7 +636,7 @@ function AgendaView(element, calendar, viewName) {
 		for (var i=0; i<colCnt; i++) { // loop through the day columns
 
 			var dayStart = cellToDate(0, i);
-			var dayEnd = dayStart.clone().add('days', 1);
+			var dayEnd = dayStart.clone().add(1, 'days');
 
 			var stretchStart = dayStart < overlayStart ? overlayStart : dayStart; // the max of the two
 			var stretchEnd = dayEnd < overlayEnd ? dayEnd : overlayEnd; // the min of the two
@@ -802,7 +802,7 @@ function AgendaView(element, calendar, viewName) {
 			return start.clone().add(slotDuration);
 		}
 		else {
-			return start.clone().add('days', 1);
+			return start.clone().add(1, 'days');
 		}
 	}
 	
diff --git a/src/agenda/AgendaWeekView.js b/src/agenda/AgendaWeekView.js
index 4b101c8..1289b9e 100644
--- a/src/agenda/AgendaWeekView.js
+++ b/src/agenda/AgendaWeekView.js
@@ -15,14 +15,14 @@ function AgendaWeekView(element, calendar) { // TODO: do a WeekView mixin
 
 
 	function incrementDate(date, delta) {
-		return date.clone().stripTime().add('weeks', delta).startOf('week');
+		return date.clone().stripTime().add(delta, 'weeks').startOf('week');
 	}
 
 
 	function render(date) {
 
 		t.intervalStart = date.clone().stripTime().startOf('week');
-		t.intervalEnd = t.intervalStart.clone().add('weeks', 1);
+		t.intervalEnd = t.intervalStart.clone().add(1, 'weeks');
 
 		t.start = t.skipHiddenDays(t.intervalStart);
 		t.end = t.skipHiddenDays(t.intervalEnd, -1, true);
diff --git a/src/basic/BasicDayView.js b/src/basic/BasicDayView.js
index 00feab8..985febc 100644
--- a/src/basic/BasicDayView.js
+++ b/src/basic/BasicDayView.js
@@ -15,7 +15,7 @@ function BasicDayView(element, calendar) { // TODO: make a DayView mixin
 
 
 	function incrementDate(date, delta) {
-		var out = date.clone().stripTime().add('days', delta);
+		var out = date.clone().stripTime().add(delta, 'days');
 		out = t.skipHiddenDays(out, delta < 0 ? -1 : 1);
 		return out;
 	}
@@ -24,7 +24,7 @@ function BasicDayView(element, calendar) { // TODO: make a DayView mixin
 	function render(date) {
 
 		t.start = t.intervalStart = date.clone().stripTime();
-		t.end = t.intervalEnd = t.start.clone().add('days', 1);
+		t.end = t.intervalEnd = t.start.clone().add(1, 'days');
 
 		t.title = calendar.formatDate(t.start, t.opt('titleFormat'));
 
diff --git a/src/basic/BasicView.js b/src/basic/BasicView.js
index 538de6c..c5210e0 100644
--- a/src/basic/BasicView.js
+++ b/src/basic/BasicView.js
@@ -388,7 +388,7 @@ function BasicView(element, calendar, viewName) {
 	
 	
 	function defaultSelectionEnd(start) {
-		return start.clone().stripTime().add('days', 1);
+		return start.clone().stripTime().add(1, 'days');
 	}
 	
 	
diff --git a/src/basic/BasicWeekView.js b/src/basic/BasicWeekView.js
index 39b3b84..e102ed7 100644
--- a/src/basic/BasicWeekView.js
+++ b/src/basic/BasicWeekView.js
@@ -15,14 +15,14 @@ function BasicWeekView(element, calendar) { // TODO: do a WeekView mixin
 
 
 	function incrementDate(date, delta) {
-		return date.clone().stripTime().add('weeks', delta).startOf('week');
+		return date.clone().stripTime().add(delta, 'weeks').startOf('week');
 	}
 
 
 	function render(date) {
 
 		t.intervalStart = date.clone().stripTime().startOf('week');
-		t.intervalEnd = t.intervalStart.clone().add('weeks', 1);
+		t.intervalEnd = t.intervalStart.clone().add(1, 'weeks');
 
 		t.start = t.skipHiddenDays(t.intervalStart);
 		t.end = t.skipHiddenDays(t.intervalEnd, -1, true);
diff --git a/src/basic/MonthView.js b/src/basic/MonthView.js
index fb330fa..c77f810 100644
--- a/src/basic/MonthView.js
+++ b/src/basic/MonthView.js
@@ -15,14 +15,14 @@ function MonthView(element, calendar) {
 
 
 	function incrementDate(date, delta) {
-		return date.clone().stripTime().add('months', delta).startOf('month');
+		return date.clone().stripTime().add(delta, 'months').startOf('month');
 	}
 
 
 	function render(date) {
 
 		t.intervalStart = date.clone().stripTime().startOf('month');
-		t.intervalEnd = t.intervalStart.clone().add('months', 1);
+		t.intervalEnd = t.intervalStart.clone().add(1, 'months');
 
 		t.start = t.intervalStart.clone();
 		t.start = t.skipHiddenDays(t.start); // move past the first week if no visible days
@@ -31,14 +31,14 @@ function MonthView(element, calendar) {
 
 		t.end = t.intervalEnd.clone();
 		t.end = t.skipHiddenDays(t.end, -1, true); // move in from the last week if no visible days
-		t.end.add('days', (7 - t.end.weekday()) % 7); // move to end of week if not already
+		t.end.add((7 - t.end.weekday()) % 7, 'days'); // move to end of week if not already
 		t.end = t.skipHiddenDays(t.end, -1, true); // move in from the last invisible days of the week
 
 		var rowCnt = Math.ceil( // need to ceil in case there are hidden days
 			t.end.diff(t.start, 'weeks', true) // returnfloat=true
 		);
 		if (t.opt('weekMode') == 'fixed') {
-			t.end.add('weeks', 6 - rowCnt);
+			t.end.add(6 - rowCnt, 'weeks');
 			rowCnt = 6;
 		}
 
diff --git a/src/common/DayEventRenderer.js b/src/common/DayEventRenderer.js
index daacdc1..36e1cd4 100644
--- a/src/common/DayEventRenderer.js
+++ b/src/common/DayEventRenderer.js
@@ -581,10 +581,10 @@ function DayEventRenderer() {
 						var origCellDate = cellToDate(origCell);
 						var cellDate = cellToDate(cell);
 						dayDelta = cellDate.diff(origCellDate, 'days');
-						eventStart = event.start.clone().add('days', dayDelta);
+						eventStart = event.start.clone().add(dayDelta, 'days');
 						renderDayOverlay(
 							eventStart,
-							getEventEnd(event).add('days', dayDelta)
+							getEventEnd(event).add(dayDelta, 'days')
 						);
 					}
 					else {
@@ -664,7 +664,7 @@ function DayEventRenderer() {
 						cellOffsetToDayOffset(cellOffset) -
 						cellOffsetToDayOffset(origCellOffset);
 
-					eventEnd = getEventEnd(event).add('days', dayDelta); // assumed to already have a stripped time
+					eventEnd = getEventEnd(event).add(dayDelta, 'days'); // assumed to already have a stripped time
 
 					if (dayDelta) {
 						eventCopy.end = eventEnd;
diff --git a/src/common/SelectionManager.js b/src/common/SelectionManager.js
index 7b613ad..46453e2 100644
--- a/src/common/SelectionManager.js
+++ b/src/common/SelectionManager.js
@@ -91,7 +91,7 @@ function SelectionManager() {
 					dates = [ cellToDate(origCell), cellToDate(cell) ].sort(dateCompare);
 					renderSelection(
 						dates[0],
-						dates[1].clone().add('days', 1) // make exclusive
+						dates[1].clone().add(1, 'days') // make exclusive
 					);
 				}else{
 					dates = null;
@@ -105,7 +105,7 @@ function SelectionManager() {
 					}
 					reportSelection(
 						dates[0],
-						dates[1].clone().add('days', 1), // make exclusive
+						dates[1].clone().add(1, 'days'), // make exclusive
 						ev
 					);
 				}
diff --git a/src/common/View.js b/src/common/View.js
index 4d85dca..b976008 100644
--- a/src/common/View.js
+++ b/src/common/View.js
@@ -331,7 +331,7 @@ function View(element, calendar, viewName) {
 		while (
 			isHiddenDayHash[(out.day() + (isExclusive ? inc : 0) + 7) % 7]
 		) {
-			out.add('days', inc);
+			out.add(inc, 'days');
 		}
 		return out;
 	}
@@ -385,7 +385,7 @@ function View(element, calendar, viewName) {
 
 	// day offset -> date
 	function dayOffsetToDate(dayOffset) {
-		return t.start.clone().add('days', dayOffset);
+		return t.start.clone().add(dayOffset, 'days');
 	}