diff --git a/lib/toxi/geom/Ellipse.js b/lib/toxi/geom/Ellipse.js
index fe67164..d843a5b 100644
--- a/lib/toxi/geom/Ellipse.js
+++ b/lib/toxi/geom/Ellipse.js
@@ -57,6 +57,11 @@ Ellipse = function(a,b,c,d) {
 extend(Ellipse,Vec2D);
 
 Ellipse.prototype.containsPoint = function(p) {
+    // Immediately reject points outside the containing rectangle
+    if (mathUtils.abs(p.x - this.x) > this.radius.x ||
+        mathUtils.abs(p.y - this.y) > this.radius.y) {
+        return false;
+    }
     var foci = this.getFoci();
     return p.distanceTo(foci[0]) + p.distanceTo(foci[1]) < 2 * mathUtils.max(this.radius.x, this.radius.y);
 };
@@ -90,15 +95,16 @@ Ellipse.prototype.getCircumference = function() {
  * @return the focus
  */
 Ellipse.prototype.getFoci = function() {
-    var foci = [];
     if (this.radius.x > this.radius.y) {
-        foci[0] = this.sub(this.focus, 0);
-        foci[1] = this.add(this.focus, 0);
-    } else {
-        foci[0] = this.sub(0, this.focus);
-        foci[1] = this.add(0, this.focus);
+        return [
+            this.sub(this.focus, 0),
+            this.add(this.focus, 0)
+        ];
     }
-    return foci;
+    return [
+        this.sub(0, this.focus),
+        this.add(0, this.focus)
+    ];
 };
 
 /**
@@ -122,7 +128,13 @@ Ellipse.prototype.setRadii = function(rx,ry) {
 		rx = rx.x;
 	}
     this.radius.set(rx, ry);
-    this.focus = this.radius.magnitude();
+
+    if (this.radius.x > this.radius.y) {
+        this.focus = Math.sqrt(this.radius.x * this.radius.x - this.radius.y * this.radius.y);
+    } else {
+        this.focus = Math.sqrt(this.radius.y * this.radius.y - this.radius.x * this.radius.x);
+    }
+
     return this;
 };
 
diff --git a/test/geom.Ellipse.js b/test/geom.Ellipse.js
index bae8aa0..455af9f 100644
--- a/test/geom.Ellipse.js
+++ b/test/geom.Ellipse.js
@@ -14,4 +14,60 @@ describe('toxi.geom.Ellipse', function(){
 			});
 		});
 	});
+    describe('#containsPoint', function(){
+        describe('tall ellipse', function(){
+             var ellipse = new toxi.geom.Ellipse(100, 100, 20, 50);
+            it('should return true for the center', function(){
+                var p = new toxi.geom.Vec2D(100, 100);
+                assert.equal(ellipse.containsPoint(p), true);
+            });
+            it('should return true for an internal point', function(){
+                var p = new toxi.geom.Vec2D(110, 110);
+                assert.equal(ellipse.containsPoint(p), true);
+            });
+            it('should return true for a point inside the top edge', function(){
+                var p = new toxi.geom.Vec2D(100, 149.9);
+                assert.equal(ellipse.containsPoint(p), true);
+            });
+            it('should return true for a point inside the right edge', function(){
+                var p = new toxi.geom.Vec2D(119.9, 100);
+                assert.equal(ellipse.containsPoint(p), true);
+            });
+            it('should return false for a point outside the ellipse', function(){
+                var p = new toxi.geom.Vec2D(119, 149);
+                assert.equal(ellipse.containsPoint(p), false);
+            });
+            it('should return false for a point outside the containing rectangle of the ellipse', function(){
+                var p = new toxi.geom.Vec2D(125, 155);
+                assert.equal(ellipse.containsPoint(p), false);
+            });
+        });
+        describe('wide ellipse', function(){
+             var ellipse = new toxi.geom.Ellipse(100, 100, 50, 20);
+            it('should return true for the center', function(){
+                var p = new toxi.geom.Vec2D(100, 100);
+                assert.equal(ellipse.containsPoint(p), true);
+            });
+            it('should return true for an internal point', function(){
+                var p = new toxi.geom.Vec2D(110, 110);
+                assert.equal(ellipse.containsPoint(p), true);
+            });
+            it('should return true for a point inside the top edge', function(){
+                var p = new toxi.geom.Vec2D(100, 119.9);
+                assert.equal(ellipse.containsPoint(p), true);
+            });
+            it('should return true for a point inside the right edge', function(){
+                var p = new toxi.geom.Vec2D(149.9, 100);
+                assert.equal(ellipse.containsPoint(p), true);
+            });
+            it('should return false for a point outside the ellipse', function(){
+                var p = new toxi.geom.Vec2D(149, 119);
+                assert.equal(ellipse.containsPoint(p), false);
+            });
+            it('should return false for a point outside the containing rectangle of the ellipse', function(){
+                var p = new toxi.geom.Vec2D(155, 125);
+                assert.equal(ellipse.containsPoint(p), false);
+            });
+        });
+    });
 });