diff --git a/src/controllers/controller.bar.js b/src/controllers/controller.bar.js
index 29256cd30df..dc391fd8958 100644
--- a/src/controllers/controller.bar.js
+++ b/src/controllers/controller.bar.js
@@ -106,23 +106,14 @@ module.exports = function(Chart) {
 			if (yScale.options.stacked) {
 				var chart = me.chart;
 				var datasets = chart.data.datasets;
-				var value = datasets[datasetIndex].data[index];
+				var value = Number(datasets[datasetIndex].data[index]);
 
-				if (value < 0) {
-					for (var i = 0; i < datasetIndex; i++) {
-						var negDS = datasets[i];
-						var negDSMeta = chart.getDatasetMeta(i);
-						if (negDSMeta.bar && negDSMeta.yAxisID === yScale.id && chart.isDatasetVisible(i)) {
-							base += negDS.data[index] < 0 ? negDS.data[index] : 0;
-						}
-					}
-				} else {
-					for (var j = 0; j < datasetIndex; j++) {
-						var posDS = datasets[j];
-						var posDSMeta = chart.getDatasetMeta(j);
-						if (posDSMeta.bar && posDSMeta.yAxisID === yScale.id && chart.isDatasetVisible(j)) {
-							base += posDS.data[index] > 0 ? posDS.data[index] : 0;
-						}
+				for (var i = 0; i < datasetIndex; i++) {
+					var currentDs = datasets[i];
+					var currentDsMeta = chart.getDatasetMeta(i);
+					if (currentDsMeta.bar && currentDsMeta.yAxisID === yScale.id && chart.isDatasetVisible(i)) {
+						var currentVal = Number(currentDs.data[index]);
+						base += value < 0 ? Math.min(currentVal, 0) : Math.max(currentVal, 0);
 					}
 				}
 
@@ -216,7 +207,7 @@ module.exports = function(Chart) {
 			var me = this;
 			var meta = me.getMeta();
 			var yScale = me.getScaleForId(meta.yAxisID);
-			var value = me.getDataset().data[index];
+			var value = Number(me.getDataset().data[index]);
 
 			if (yScale.options.stacked) {
 
@@ -227,10 +218,11 @@ module.exports = function(Chart) {
 					var ds = me.chart.data.datasets[i];
 					var dsMeta = me.chart.getDatasetMeta(i);
 					if (dsMeta.bar && dsMeta.yAxisID === yScale.id && me.chart.isDatasetVisible(i)) {
-						if (ds.data[index] < 0) {
-							sumNeg += ds.data[index] || 0;
+						var stackedVal = Number(ds.data[index]);
+						if (stackedVal < 0) {
+							sumNeg += stackedVal || 0;
 						} else {
-							sumPos += ds.data[index] || 0;
+							sumPos += stackedVal || 0;
 						}
 					}
 				}
@@ -454,24 +446,16 @@ module.exports = function(Chart) {
 			var base = 0;
 
 			if (xScale.options.stacked) {
+				var chart = me.chart;
+				var datasets = chart.data.datasets;
+				var value = Number(datasets[datasetIndex].data[index]);
 
-				var value = me.chart.data.datasets[datasetIndex].data[index];
-
-				if (value < 0) {
-					for (var i = 0; i < datasetIndex; i++) {
-						var negDS = me.chart.data.datasets[i];
-						var negDSMeta = me.chart.getDatasetMeta(i);
-						if (negDSMeta.bar && negDSMeta.xAxisID === xScale.id && me.chart.isDatasetVisible(i)) {
-							base += negDS.data[index] < 0 ? negDS.data[index] : 0;
-						}
-					}
-				} else {
-					for (var j = 0; j < datasetIndex; j++) {
-						var posDS = me.chart.data.datasets[j];
-						var posDSMeta = me.chart.getDatasetMeta(j);
-						if (posDSMeta.bar && posDSMeta.xAxisID === xScale.id && me.chart.isDatasetVisible(j)) {
-							base += posDS.data[index] > 0 ? posDS.data[index] : 0;
-						}
+				for (var i = 0; i < datasetIndex; i++) {
+					var currentDs = datasets[i];
+					var currentDsMeta = chart.getDatasetMeta(i);
+					if (currentDsMeta.bar && currentDsMeta.xAxisID === xScale.id && chart.isDatasetVisible(i)) {
+						var currentVal = Number(currentDs.data[index]);
+						base += value < 0 ? Math.min(currentVal, 0) : Math.max(currentVal, 0);
 					}
 				}
 
@@ -528,7 +512,7 @@ module.exports = function(Chart) {
 			var me = this;
 			var meta = me.getMeta();
 			var xScale = me.getScaleForId(meta.xAxisID);
-			var value = me.getDataset().data[index];
+			var value = Number(me.getDataset().data[index]);
 
 			if (xScale.options.stacked) {
 
@@ -539,10 +523,11 @@ module.exports = function(Chart) {
 					var ds = me.chart.data.datasets[i];
 					var dsMeta = me.chart.getDatasetMeta(i);
 					if (dsMeta.bar && dsMeta.xAxisID === xScale.id && me.chart.isDatasetVisible(i)) {
-						if (ds.data[index] < 0) {
-							sumNeg += ds.data[index] || 0;
+						var stackedVal = Number(ds.data[index]);
+						if (stackedVal < 0) {
+							sumNeg += stackedVal || 0;
 						} else {
-							sumPos += ds.data[index] || 0;
+							sumPos += stackedVal || 0;
 						}
 					}
 				}
diff --git a/src/controllers/controller.line.js b/src/controllers/controller.line.js
index f3d7328d431..66962769413 100644
--- a/src/controllers/controller.line.js
+++ b/src/controllers/controller.line.js
@@ -221,7 +221,7 @@ module.exports = function(Chart) {
 					ds = chart.data.datasets[i];
 					dsMeta = chart.getDatasetMeta(i);
 					if (dsMeta.type === 'line' && chart.isDatasetVisible(i)) {
-						var stackedRightValue = yScale.getRightValue(ds.data[index]);
+						var stackedRightValue = Number(yScale.getRightValue(ds.data[index]));
 						if (stackedRightValue < 0) {
 							sumNeg += stackedRightValue || 0;
 						} else {
@@ -230,7 +230,7 @@ module.exports = function(Chart) {
 					}
 				}
 
-				var rightValue = yScale.getRightValue(value);
+				var rightValue = Number(yScale.getRightValue(value));
 				if (rightValue < 0) {
 					return yScale.getPixelForValue(sumNeg + rightValue);
 				} else {
diff --git a/test/controller.bar.tests.js b/test/controller.bar.tests.js
index 560b767940f..f997dcb4b74 100644
--- a/test/controller.bar.tests.js
+++ b/test/controller.bar.tests.js
@@ -285,6 +285,60 @@ describe('Bar controller tests', function() {
 		});
 	});
 
+	it('should update elements when the scales are stacked and data is strings', function() {
+		var chart = window.acquireChart({
+			type: 'bar',
+			data: {
+				datasets: [{
+					data: ['10', '-10', '10', '-10'],
+					label: 'dataset1'
+				}, {
+					data: ['10', '15', '0', '-4'],
+					label: 'dataset2'
+				}],
+				labels: ['label1', 'label2', 'label3', 'label4']
+			},
+			options: {
+				scales: {
+					xAxes: [{
+						type: 'category',
+						stacked: true
+					}],
+					yAxes: [{
+						type: 'linear',
+						stacked: true
+					}]
+				}
+			}
+		});
+
+		var meta0 = chart.getDatasetMeta(0);
+
+		[	{ b: 290, w: 91, x:  95, y: 161 },
+			{ b: 290, w: 91, x: 209, y: 419 },
+			{ b: 290, w: 91, x: 322, y: 161 },
+			{ b: 290, w: 91, x: 436, y: 419 }
+		].forEach(function(values, i) {
+			expect(meta0.data[i]._model.base).toBeCloseToPixel(values.b);
+			expect(meta0.data[i]._model.width).toBeCloseToPixel(values.w);
+			expect(meta0.data[i]._model.x).toBeCloseToPixel(values.x);
+			expect(meta0.data[i]._model.y).toBeCloseToPixel(values.y);
+		});
+
+		var meta1 = chart.getDatasetMeta(1);
+
+		[	{ b: 161, w: 91, x:  95, y:  32 },
+			{ b: 290, w: 91, x: 209, y:  97 },
+			{ b: 161, w: 91, x: 322, y: 161 },
+			{ b: 419, w: 91, x: 436, y: 471 }
+		].forEach(function(values, i) {
+			expect(meta1.data[i]._model.base).toBeCloseToPixel(values.b);
+			expect(meta1.data[i]._model.width).toBeCloseToPixel(values.w);
+			expect(meta1.data[i]._model.x).toBeCloseToPixel(values.x);
+			expect(meta1.data[i]._model.y).toBeCloseToPixel(values.y);
+		});
+	});
+
 	it('should draw all bars', function() {
 		var chart = window.acquireChart({
 			type: 'bar',
diff --git a/test/controller.line.tests.js b/test/controller.line.tests.js
index 78aecf2d2ad..0417054758e 100644
--- a/test/controller.line.tests.js
+++ b/test/controller.line.tests.js
@@ -348,6 +348,52 @@ describe('Line controller tests', function() {
 		
 	});
 
+	it('should update elements when the y scale is stacked and data is strings', function() {
+		var chart = window.acquireChart({
+			type: 'line',
+			data: {
+				datasets: [{
+					data: ['10', '-10', '10', '-10'],
+					label: 'dataset1'
+				}, {
+					data: ['10', '15', '0', '-4'],
+					label: 'dataset2'
+				}],
+				labels: ['label1', 'label2', 'label3', 'label4']
+			},
+			options: {
+				scales: {
+					yAxes: [{
+						stacked: true
+					}]
+				}
+			}
+		});
+		
+		var meta0 = chart.getDatasetMeta(0);
+
+		[	{ x:  38, y: 161 },
+			{ x: 189, y: 419 },
+			{ x: 341, y: 161 },
+			{ x: 492, y: 419 }
+		].forEach(function(values, i) {
+				expect(meta0.data[i]._model.x).toBeCloseToPixel(values.x);
+				expect(meta0.data[i]._model.y).toBeCloseToPixel(values.y);
+		});
+
+		var meta1 = chart.getDatasetMeta(1);
+
+		[	{ x:  38, y:  32 },
+			{ x: 189, y:  97 },
+			{ x: 341, y: 161 },
+			{ x: 492, y: 471 }
+		].forEach(function(values, i) {
+				expect(meta1.data[i]._model.x).toBeCloseToPixel(values.x);
+				expect(meta1.data[i]._model.y).toBeCloseToPixel(values.y);
+		});
+		
+	});
+
 	it('should find the correct scale zero when the data is all positive', function() {
 		var chart = window.acquireChart({
 			type: 'line',