diff --git a/package-lock.json b/package-lock.json
index af0ee334..55a2b6e8 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,11 +1,11 @@
 {
     "name": "chs-js-lib",
-    "version": "0.2.18",
+    "version": "0.2.19",
     "lockfileVersion": 2,
     "requires": true,
     "packages": {
         "": {
-            "version": "0.2.18",
+            "version": "0.2.19",
             "license": "ISC",
             "dependencies": {
                 "tone": "^14.7.77",
diff --git a/package.json b/package.json
index 032b0af7..2a1dd77f 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
     "name": "chs-js-lib",
-    "version": "0.2.18",
+    "version": "0.2.19",
     "description": "JavaScript graphics library used in CodeHS's platform.",
     "main": "dist/chs.cjs",
     "module": "dist/chs.mjs",
diff --git a/src/graphics/index.js b/src/graphics/index.js
index c24b45ee..a6fe04ef 100644
--- a/src/graphics/index.js
+++ b/src/graphics/index.js
@@ -462,6 +462,10 @@ class GraphicsManager extends Manager {
      * @param {Thing} elem - The element to be removed from the canvas.
      */
     remove(elem) {
+        if (!(elem instanceof Thing)) {
+            return;
+        }
+
         if (elem instanceof WebVideo) {
             elem.stop();
         }
diff --git a/src/graphics/polygon.js b/src/graphics/polygon.js
index a226beaa..ce871243 100644
--- a/src/graphics/polygon.js
+++ b/src/graphics/polygon.js
@@ -215,6 +215,35 @@ class Polygon extends Thing {
         const dy = y - this.y;
         this.move(dx, dy);
     }
+
+    /**
+     * Polygons manually calculate their bounds with their own implementation of _updateBounds
+     * (rather than the implementation in the Thing superclass) because Polygon's can have
+     * negative points which draw to the left of their x value or above their y value.
+     * @private
+     */
+    _updateBounds() {
+        let minX = Infinity;
+        let maxX = -Infinity;
+        let minY = Infinity;
+        let maxY = -Infinity;
+        this.points.forEach(({ x, y }) => {
+            minX = Math.min(minX, x);
+            maxX = Math.max(maxX, x);
+            minY = Math.min(minY, y);
+            maxY = Math.max(maxY, y);
+        });
+        const width = maxX - minX;
+        const height = maxY - minY;
+        this.bounds = {
+            left: minX - this.anchor.horizontal * width,
+            right: maxX - this.anchor.horizontal * width,
+            top: minY - this.anchor.vertical * height,
+            bottom: maxY - this.anchor.vertical * height,
+        };
+        this._boundsInvalidated = false;
+        this._lastCalculatedBoundsID++;
+    }
 }
 
 export default Polygon;
diff --git a/src/graphics/thing.js b/src/graphics/thing.js
index 1ddacd4d..2002e934 100644
--- a/src/graphics/thing.js
+++ b/src/graphics/thing.js
@@ -482,7 +482,13 @@ class Thing {
             context.strokeStyle = 'red';
             context.fill();
             const bounds = this.getBounds();
-            context.strokeRect(0, 0, bounds.right - bounds.left, bounds.bottom - bounds.top);
+            context.translate(-drawX, -drawY);
+            context.strokeRect(
+                bounds.left,
+                bounds.top,
+                bounds.right - bounds.left,
+                bounds.bottom - bounds.top
+            );
         }
 
         context.restore();
diff --git a/test/graphics.test.js b/test/graphics.test.js
index 1b69c7a5..356ed6c1 100644
--- a/test/graphics.test.js
+++ b/test/graphics.test.js
@@ -302,6 +302,19 @@ describe('Graphics', () => {
             expect(g.elementPool).toEqual([a, a, b, c]);
             expect(g.elementPoolSize).toEqual(4);
         });
+        it('Removing an undefined element does not throw', () => {
+            const g = new Graphics({ shouldUpdate: false });
+            let el;
+            expect(() => {
+                g.remove(el);
+            }).not.toThrow();
+        });
+        it('Removing a non-Thing does not throw', () => {
+            const g = new Graphics({ shouldUpdate: false });
+            expect(() => {
+                g.remove(Circle);
+            }).not.toThrow();
+        });
     });
     describe('fullReset', () => {
         it('Clears all elements', () => {
diff --git a/test/polygon.test.js b/test/polygon.test.js
index 9f9c1628..90244dc2 100644
--- a/test/polygon.test.js
+++ b/test/polygon.test.js
@@ -88,4 +88,26 @@ describe('Polygon', () => {
             ]);
         });
     });
+    describe('Bounds', () => {
+        it('Handles negative points', () => {
+            const p = new Polygon();
+            p.addPoint(-30, 0);
+            p.addPoint(0, 30);
+            p.addPoint(30, 30);
+
+            expect(p.getBounds()).toEqual({
+                top: 0,
+                left: -30,
+                bottom: 30,
+                right: 30,
+            });
+            p.setAnchor({ vertical: 0.5, horizontal: 0.5 });
+            expect(p.getBounds()).toEqual({
+                top: -15,
+                left: -60,
+                bottom: 15,
+                right: 0,
+            });
+        });
+    });
 });