diff --git a/.gitignore b/.gitignore
index 8e0ef9e5fd..508f24a457 100644
--- a/.gitignore
+++ b/.gitignore
@@ -3,6 +3,7 @@ build/
 test/tests.js
 test/tests.js.map
 plottable.js
+plottable.js.map
 plottable.min.js
 
 # Typescript
diff --git a/src/plots/barPlot.ts b/src/plots/barPlot.ts
index f5fd4b8e17..ad69d8432d 100644
--- a/src/plots/barPlot.ts
+++ b/src/plots/barPlot.ts
@@ -398,7 +398,7 @@ export class Bar<X, Y> extends XYPlot<X, Y> {
   /**
    * Returns the PlotEntity nearest to the query point according to the following algorithm:
    *   - If the query point is inside a bar, returns the PlotEntity for that bar.
-   *   - Otherwise, gets the nearest PlotEntity by the primary direction (X for vertical, Y for horizontal),
+   *   - Otherwise, gets the nearest PlotEntity by the positional direction (X for vertical, Y for horizontal),
    *     breaking ties with the secondary direction.
    * Returns undefined if no PlotEntity can be found.
    *
@@ -406,72 +406,73 @@ export class Bar<X, Y> extends XYPlot<X, Y> {
    * @returns {PlotEntity} The nearest PlotEntity, or undefined if no PlotEntity can be found.
    */
   public entityNearest(queryPoint: Point): IPlotEntity {
+    return this._computeBarPixelThickness.doLocked(() => {
+      const queryPtPrimary = this._isVertical ? queryPoint.x : queryPoint.y;
+      const queryPtSecondary = this._isVertical ? queryPoint.y : queryPoint.x;
+
+      // SVGRects are positioned with sub-pixel accuracy (the default unit
+      // for the x, y, height & width attributes), but user selections (e.g. via
+      // mouse events) usually have pixel accuracy. We add a tolerance of 0.5 pixels.
+      const tolerance = 0.5;
+
+      // PERF: precompute all these values to prevent recomputing for each entity
+      const chartBounds = this.bounds();
+      const chartWidth = chartBounds.bottomRight.x - chartBounds.topLeft.x;
+      const chartHeight = chartBounds.bottomRight.y - chartBounds.topLeft.y;
+      const xRange = { min: 0, max: chartWidth };
+      const yRange = { min: 0, max: chartHeight };
+      const originalPositionProjector = Plot._scaledAccessor(this.length());
+      const scaledBaseline = this.length().scale.scale(this.baselineValue());
+      const plotPointFactory = (datum: any, index: number, dataset: Dataset, rect: IEntityBounds) => {
+        return this._pixelPointBar(originalPositionProjector(datum, index, dataset), scaledBaseline, rect);
+      };
+
+      let minPrimaryDist = Infinity;
+      let minSecondaryDist = Infinity;
+      let closest: ILightweightPlotEntity;
+      this._getEntityStore().entities().forEach((entity: ILightweightPlotEntity) => {
+        const barBBox = this._entityBounds(entity);
+        if (!Utils.DOM.intersectsBBox(xRange, yRange, barBBox)) {
+          return;
+        }
 
-    const queryPtPrimary = this._isVertical ? queryPoint.x : queryPoint.y;
-    const queryPtSecondary = this._isVertical ? queryPoint.y : queryPoint.x;
-
-    // SVGRects are positioned with sub-pixel accuracy (the default unit
-    // for the x, y, height & width attributes), but user selections (e.g. via
-    // mouse events) usually have pixel accuracy. We add a tolerance of 0.5 pixels.
-    const tolerance = 0.5;
-
-    // PERF: precompute all these values to prevent recomputing for each entity
-    const chartBounds = this.bounds();
-    const chartWidth = chartBounds.bottomRight.x - chartBounds.topLeft.x;
-    const chartHeight = chartBounds.bottomRight.y - chartBounds.topLeft.y;
-    const xRange = { min: 0, max: chartWidth };
-    const yRange = { min: 0, max: chartHeight };
-    const originalPositionProjector = (this._isVertical ? Plot._scaledAccessor(this.y()) : Plot._scaledAccessor(this.x()));
-    const scaledBaseline = (<Scale<any, any>> (this._isVertical ? this.y().scale : this.x().scale)).scale(this.baselineValue());
-    const plotPointFactory = (datum: any, index: number, dataset: Dataset, rect: IEntityBounds) => {
-      return this._pixelPointBar(originalPositionProjector(datum, index, dataset), scaledBaseline, rect);
-    };
-
-    let minPrimaryDist = Infinity;
-    let minSecondaryDist = Infinity;
-    let closest: ILightweightPlotEntity;
-    this._getEntityStore().entities().forEach((entity: ILightweightPlotEntity) => {
-      const barBBox = this._entityBounds(entity);
-      if (!Utils.DOM.intersectsBBox(xRange, yRange, barBBox)) {
-        return;
-      }
+        let primaryDist = 0;
+        let secondaryDist = 0;
+
+        // if we're inside a bar, distance in both directions should stay 0
+        if (!Utils.DOM.intersectsBBox(queryPoint.x, queryPoint.y, barBBox, tolerance)) {
+          const plotPt = plotPointFactory(entity.datum, entity.index, entity.dataset, barBBox);
+          const plotPtPrimary = this._isVertical ? plotPt.x : plotPt.y;
+          primaryDist = Math.abs(queryPtPrimary - plotPtPrimary);
+
+          // compute this bar's min and max along the secondary axis
+          const barMinSecondary = this._isVertical ? barBBox.y : barBBox.x;
+          const barMaxSecondary = barMinSecondary + (this._isVertical ? barBBox.height : barBBox.width);
+
+          if (queryPtSecondary >= barMinSecondary - tolerance && queryPtSecondary <= barMaxSecondary + tolerance) {
+            // if we're within a bar's secondary axis span, it is closest in that direction
+            secondaryDist = 0;
+          } else {
+            const plotPtSecondary = this._isVertical ? plotPt.y : plotPt.x;
+            secondaryDist = Math.abs(queryPtSecondary - plotPtSecondary);
+          }
+        }
 
-      let primaryDist = 0;
-      let secondaryDist = 0;
-
-      // if we're inside a bar, distance in both directions should stay 0
-      if (!Utils.DOM.intersectsBBox(queryPoint.x, queryPoint.y, barBBox, tolerance)) {
-        const plotPt = plotPointFactory(entity.datum, entity.index, entity.dataset, barBBox);
-        const plotPtPrimary = this._isVertical ? plotPt.x : plotPt.y;
-        primaryDist = Math.abs(queryPtPrimary - plotPtPrimary);
-
-        // compute this bar's min and max along the secondary axis
-        const barMinSecondary = this._isVertical ? barBBox.y : barBBox.x;
-        const barMaxSecondary = barMinSecondary + (this._isVertical ? barBBox.height : barBBox.width);
-
-        if (queryPtSecondary >= barMinSecondary - tolerance && queryPtSecondary <= barMaxSecondary + tolerance) {
-          // if we're within a bar's secondary axis span, it is closest in that direction
-          secondaryDist = 0;
-        } else {
-          const plotPtSecondary = this._isVertical ? plotPt.y : plotPt.x;
-          secondaryDist = Math.abs(queryPtSecondary - plotPtSecondary);
+        // if we find a closer bar, record its distance and start new closest lists
+        if (primaryDist < minPrimaryDist
+          || primaryDist === minPrimaryDist && secondaryDist < minSecondaryDist) {
+          closest = entity;
+          minPrimaryDist = primaryDist;
+          minSecondaryDist = secondaryDist;
         }
-      }
+      });
 
-      // if we find a closer bar, record its distance and start new closest lists
-      if (primaryDist < minPrimaryDist
-        || primaryDist === minPrimaryDist && secondaryDist < minSecondaryDist) {
-        closest = entity;
-        minPrimaryDist = primaryDist;
-        minSecondaryDist = secondaryDist;
+      if (closest !== undefined) {
+        return this._lightweightPlotEntityToPlotEntity(closest);
+      } else {
+        return undefined;
       }
     });
-
-    if (closest !== undefined) {
-      return this._lightweightPlotEntityToPlotEntity(closest);
-    } else {
-      return undefined;
-    }
   }
 
   /**
diff --git a/webpackConfig/build.js b/webpackConfig/build.js
index 590f9b8d54..83b7a48b38 100644
--- a/webpackConfig/build.js
+++ b/webpackConfig/build.js
@@ -46,6 +46,7 @@ Licensed under MIT (https://github.com/palantir/plottable/blob/master/LICENSE)`;
  *     a dependency on a module named "plottable" (both in AMD and CommonJS).
  */
 module.exports = {
+  devtool: "source-map",
   entry: "./build/src/index.js",
   output: {
     filename: "plottable.js",