diff --git a/spec/api/api.zoom-spec.js b/spec/api/api.zoom-spec.js
index 0ab9f6fdb..1cc8020c2 100644
--- a/spec/api/api.zoom-spec.js
+++ b/spec/api/api.zoom-spec.js
@@ -11,6 +11,8 @@ describe("API zoom", function() {
 	let chart;
 
 	describe("zoom line chart #1", () => {
+		const spy = sinon.spy();
+
 		before(() => {
 			chart = util.generate({
 				data: {
@@ -21,7 +23,8 @@ describe("API zoom", function() {
 					]
 				},
 				zoom: {
-					enabled: true
+					enabled: true,
+					onzoom: spy
 				}
 			});
 		});
@@ -35,6 +38,10 @@ describe("API zoom", function() {
 
 			expect(domain[0]).to.be.equal(target[0]);
 			expect(domain[1]).to.be.equal(target[1]);
+
+			// onzoom callback has been called?
+			expect(spy.called).to.be.true;
+			expect(spy.args[0][0]).to.be.deep.equal(target);
 		});
 
 		it("should be zoomed properly again", () => {
diff --git a/spec/interactions/zoom-spec.js b/spec/interactions/zoom-spec.js
index fe7ddf029..80fb18453 100644
--- a/spec/interactions/zoom-spec.js
+++ b/spec/interactions/zoom-spec.js
@@ -123,6 +123,8 @@ describe("ZOOM", function() {
 				return new Promise((resolve, reject) => {
 					setTimeout(() => {
 						if (spyOnZoomStart.called) {
+							expect(spyOnZoomStart.args[0][0].type).to.be.equal("mousedown");
+
 							util.fireEvent(eventRect, "mousemove", {
 								clientX: 100,
 								clientY: 150
@@ -138,17 +140,17 @@ describe("ZOOM", function() {
 				return new Promise((resolve, reject) => {
 					setTimeout(() => {
 						if (spyOnZoom.called) {
-							if (spyOnZoom.called) {
-								util.fireEvent(eventRect, "mouseup", {
-									clientX: 100,
-									clientY: 150
-								}, chart);
+							expect(spyOnZoom.args[0][0]).to.be.deep.equal([0, 3]);
+
+							util.fireEvent(eventRect, "mouseup", {
+								clientX: 100,
+								clientY: 150
+							}, chart);
 
-								// call explicitly, due to mouseup isn't firing well programmatically.
-								chart.internal.onZoomEnd();
+							// call explicitly, due to mouseup isn't firing well programmatically.
+							chart.internal.onZoomEnd();
 
-								resolve("--> onzoom callback called!");
-							}
+							resolve("--> onzoom callback called!");
 						};
 					}, 500);
 				})
diff --git a/src/api/api.zoom.js b/src/api/api.zoom.js
index 916358605..aa217acda 100644
--- a/src/api/api.zoom.js
+++ b/src/api/api.zoom.js
@@ -70,7 +70,7 @@ const zoom = function(domainValue) {
 		});
 
 		$$.setZoomResetButton();
-		callFn($$.config.zoom_onzoom, resultDomain);
+		callFn($$.config.zoom_onzoom, $$.api, resultDomain);
 	} else {
 		resultDomain = $$.zoomScale ?
 			$$.zoomScale.domain() : $$.x.orgDomain();