diff --git a/pointer.js b/pointer.js
index 5eb9341..5b3e9eb 100644
--- a/pointer.js
+++ b/pointer.js
@@ -86,7 +86,8 @@ export class Pointer {
     // Monitor wheel events
     el.addEventListener('wheel', e => {
       const factor = e.deltaY > 0 ? ZOOM_IN_FACTOR : ZOOM_OUT_FACTOR;
-      this.sim.scheduleZoom({x: e.clientX, y: e.clientY}, factor);
+      const {x, y} = this.sim.screenToSim(e.clientX, e.clientY);
+      this.sim.scheduleZoom({x, y}, factor);
     });
 
   }
diff --git a/simulator.js b/simulator.js
index a6b6c5a..695a1e7 100644
--- a/simulator.js
+++ b/simulator.js
@@ -56,12 +56,13 @@ export class Sim {
     this.nextZoom = {x, y, factor};
   }
 
-  zoom({x: screenX, y: screenY, factor}) {
-    const {x, y} = this.screenToSim(screenX, screenY);
+  // x, y should be in Sim coordinates
+  zoom({x, y, factor}) {
     // x, y are the mouse coordinates, which should be the center of the new view frame
     // the new view origin should be x, y minus half the new view width and height
     // compute new scale
     this.display.scalePower += factor;
+    // TODO: Lossy rescaling to expand zoom range
     if (this.display.scalePower > SCALE_POWER_MAX) this.display.scalePower = SCALE_POWER_MAX;
     if (this.display.scalePower < SCALE_POWER_MIN) this.display.scalePower = SCALE_POWER_MIN;
     // compute coordinates of new view frame
@@ -71,7 +72,7 @@ export class Sim {
     this.pointer.clearPointerHistory();
     if (this.pointer.panning) {
       this.pointer.panning = undefined;
-      // TODO: Maybe rescale velocity
+      // TODO: Maybe show velocity vectors relative to view velocity
     }
   }
 
diff --git a/tool/zoom.js b/tool/zoom.js
index 2d6b993..317e488 100644
--- a/tool/zoom.js
+++ b/tool/zoom.js
@@ -24,21 +24,21 @@ export class Zoom extends Tool {
     zoomIn.innerHTML = '<h2>Zoom<br>In</h2>';
     zoomAll.innerHTML = '<h2>Zoom to Fit</h2>';
 
-    zoomOut.addEventListener('click', (e) => {
+    zoomOut.addEventListener('click', () => {
       // Aim at center of view
       const x = this.sim.display.width * this.sim.display.scale / 2;
       const y = this.sim.display.height * this.sim.display.scale / 2;
-      this.sim.scheduleZoom({x, y}, ZOOM_OUT_FACTOR);
+      this.sim.scheduleZoom(this.sim.screenToSim(x, y), ZOOM_OUT_FACTOR);
     });
 
-    zoomIn.addEventListener('click', (e) => {
+    zoomIn.addEventListener('click', () => {
       // Aim at center of view
       const x = this.sim.display.width * this.sim.display.scale / 2;
       const y = this.sim.display.height * this.sim.display.scale / 2;
-      this.sim.scheduleZoom({x, y}, ZOOM_IN_FACTOR);
+      this.sim.scheduleZoom(this.sim.screenToSim(x, y), ZOOM_IN_FACTOR);
     });
 
-    zoomAll.addEventListener('click', (e) => {
+    zoomAll.addEventListener('click', () => {
       // Determine bounding box
       const box = this.sim.objects.boundingBox;
       const x = (box.start.x + box.end.x) / 2;
@@ -47,13 +47,10 @@ export class Zoom extends Tool {
         const widthRatio = Math.abs(box.start.x - box.end.x) / this.sim.display.width;
         const heightRatio = Math.abs(box.start.y - box.end.y) / this.sim.display.height;
         const biggerRatio = Math.max(widthRatio, heightRatio);
-        if (biggerRatio <= 1) {
-          const base2Ratio = Math.log(1/biggerRatio) / Math.log(2);
-          this.sim.scheduleZoom({x, y}, Math.floor(base2Ratio));
-        } else {
-          const base2Ratio = Math.log(1/biggerRatio) / Math.log(2);
-          this.sim.scheduleZoom({x, y}, Math.ceil(base2Ratio));
-        }
+        const base2factor = Math.log(1/biggerRatio) / Math.log(2);
+        const factor = Math.floor(base2factor) - 1;
+        console.log({biggerRatio, base2factor, factor});
+        this.sim.scheduleZoom({x, y}, factor);
       }
     });
   }