diff --git a/src/ol/control/overviewmap.js b/src/ol/control/overviewmap.js
index f72771f6aa..874021aff2 100644
--- a/src/ol/control/overviewmap.js
+++ b/src/ol/control/overviewmap.js
@@ -371,8 +371,6 @@ ol.control.OverviewMap.prototype.updateBox_ = function() {
 
   var ovview = ovmap.getView();
 
-  var ovmapSize = ovmap.getSize();
-
   var rotation = view.getRotation();
 
   var overlay = this.boxOverlay_;
diff --git a/src/ol/format/esrijson.js b/src/ol/format/esrijson.js
index 6e006d2ba8..b183f80b12 100644
--- a/src/ol/format/esrijson.js
+++ b/src/ol/format/esrijson.js
@@ -315,7 +315,9 @@ ol.format.EsriJSON.writeLineStringGeometry_ = function(geometry, opt_options) {
   return /** @type {EsriJSONPolyline} */ ({
     hasZ: hasZM.hasZ,
     hasM: hasZM.hasM,
-    paths: [/** @type {ol.geom.LineString} */ (geometry).getCoordinates()]
+    paths: [
+      /** @type {ol.geom.LineString} */ (geometry).getCoordinates()
+    ]
   });
 };
 
diff --git a/src/ol/format/gml3.js b/src/ol/format/gml3.js
index 8615f09383..fb8f687e4a 100644
--- a/src/ol/format/gml3.js
+++ b/src/ol/format/gml3.js
@@ -911,7 +911,6 @@ ol.format.GML3.prototype.writeRing_ = function(node, ring, objectStack) {
  * @private
  */
 ol.format.GML3.prototype.writeSurfaceOrPolygonMember_ = function(node, polygon, objectStack) {
-  var context = objectStack[objectStack.length - 1];
   var child = this.GEOMETRY_NODE_FACTORY_(
       polygon, objectStack);
   if (child) {
@@ -941,7 +940,6 @@ ol.format.GML3.prototype.writePointMember_ = function(node, point, objectStack)
  * @private
  */
 ol.format.GML3.prototype.writeLineStringOrCurveMember_ = function(node, line, objectStack) {
-  var context = objectStack[objectStack.length - 1];
   var child = this.GEOMETRY_NODE_FACTORY_(line, objectStack);
   if (child) {
     node.appendChild(child);
diff --git a/src/ol/interaction/modify.js b/src/ol/interaction/modify.js
index c934d14c08..e75cce885c 100644
--- a/src/ol/interaction/modify.js
+++ b/src/ol/interaction/modify.js
@@ -709,7 +709,6 @@ ol.interaction.Modify.handleEvent = function(mapBrowserEvent) {
   if (this.vertexFeature_ && this.deleteCondition_(mapBrowserEvent)) {
     if (mapBrowserEvent.type != ol.MapBrowserEvent.EventType.SINGLECLICK ||
         !this.ignoreNextSingleClick_) {
-      var geometry = /** @type {ol.geom.Point} */ (this.vertexFeature_.getGeometry());
       handled = this.removePoint();
     } else {
       handled = true;
diff --git a/src/ol/math.js b/src/ol/math.js
index cd1e3dfd57..96892c6818 100644
--- a/src/ol/math.js
+++ b/src/ol/math.js
@@ -1,7 +1,6 @@
 goog.provide('ol.math');
 
 
-
 /**
  * Takes a number and clamps it to within the provided bounds.
  * @param {number} value The input number.
diff --git a/src/ol/renderer/dom/vectorlayer.js b/src/ol/renderer/dom/vectorlayer.js
index ae70e64efb..70ac946023 100644
--- a/src/ol/renderer/dom/vectorlayer.js
+++ b/src/ol/renderer/dom/vectorlayer.js
@@ -103,9 +103,6 @@ ol.renderer.dom.VectorLayer.prototype.clearFrame = function() {
  * @inheritDoc
  */
 ol.renderer.dom.VectorLayer.prototype.composeFrame = function(frameState, layerState) {
-
-  var vectorLayer = /** @type {ol.layer.Vector} */ (this.getLayer());
-
   var viewState = frameState.viewState;
   var viewCenter = viewState.center;
   var viewRotation = viewState.rotation;
diff --git a/test/node/.eslintrc b/test/node/.eslintrc
index 22abc7fb2b..60b5f72125 100644
--- a/test/node/.eslintrc
+++ b/test/node/.eslintrc
@@ -1,5 +1,6 @@
 {
   "env": {
-    "es6": true
+    "es6": true,
+    "mocha": true
   }
 }
diff --git a/test/node/one-provide.js b/test/node/one-provide.js
index 22cad85a3a..9205746ca6 100644
--- a/test/node/one-provide.js
+++ b/test/node/one-provide.js
@@ -5,7 +5,7 @@ const path = require('path');
 
 const src = path.join(__dirname, '..', '..', 'src');
 
-const PROVIDE_RE = /^goog.provide\('(.*)'\);/
+const PROVIDE_RE = /^goog.provide\('(.*)'\);/;
 
 describe('each file', () => {
 
diff --git a/test/spec/ol/format/wfs.test.js b/test/spec/ol/format/wfs.test.js
index 5c8d91a422..7a0b34d272 100644
--- a/test/spec/ol/format/wfs.test.js
+++ b/test/spec/ol/format/wfs.test.js
@@ -672,7 +672,7 @@ describe('ol.format.WFS', function() {
         [-12240318, 6507071],
         [-12416429, 6604910]
       ]]));
-      var error = false;
+
       expect(function() {
         format.writeTransaction(null, [updateFeature], null, {
           featureNS: 'http://foo',
diff --git a/test/spec/ol/ol.test.js b/test/spec/ol/ol.test.js
index ebb8f50b68..56b8faa6c6 100644
--- a/test/spec/ol/ol.test.js
+++ b/test/spec/ol/ol.test.js
@@ -29,7 +29,7 @@ describe('ol', function() {
     it('has a name', function() {
       var error = new ol.AssertionError(42);
       expect(error.name).to.be('AssertionError');
-    })
+    });
   });
 
 });
diff --git a/test/spec/ol/structs/priorityqueue.test.js b/test/spec/ol/structs/priorityqueue.test.js
index f969b8b7b9..a1e12ecdcd 100644
--- a/test/spec/ol/structs/priorityqueue.test.js
+++ b/test/spec/ol/structs/priorityqueue.test.js
@@ -16,7 +16,7 @@ describe('ol.structs.PriorityQueue', function() {
         if (!assertion) {
           throw new Error(message);
         }
-      }
+      };
       pq = new ol.structs.PriorityQueue(
           identity, identity);
     });