diff --git a/types/opentype.js/index.d.ts b/types/opentype.js/index.d.ts
index 8dc449784d..5fdc257362 100644
--- a/types/opentype.js/index.d.ts
+++ b/types/opentype.js/index.d.ts
@@ -367,8 +367,19 @@ export interface PathCommand {
  * UTIL CLASSES
  ******************************************/
 
-export type BoundingBox = () => any;
-// TODO add methods
+export class BoundingBox {
+    x1: number;
+    y1: number;
+    x2: number;
+    y2: number;
+
+    isEmpty(): boolean;
+    addPoint(x: number, y: number): void;
+    addX(x: number): void;
+    addY(y: number): void;
+    addBezier(x0: number, y0: number, x1: number, y1: number, x2: number, y2: number, x: number, y: number): void;
+    addQuad(x0: number, y0: number, x1: number, y1: number, x: number, y: number): void;
+}
 
 export interface Encoding {
     charset: string;
diff --git a/types/opentype.js/opentype.js-tests.ts b/types/opentype.js/opentype.js-tests.ts
index 04781d5415..e3695944db 100644
--- a/types/opentype.js/opentype.js-tests.ts
+++ b/types/opentype.js/opentype.js-tests.ts
@@ -113,6 +113,8 @@ aPath.extend(aPath);
 aPath.extend(aPath.commands);
 aPath.extend(aPath.getBoundingBox());
 const pathBBox: opentype.BoundingBox = aPath.getBoundingBox();
+pathBBox.addQuad(1, 1, 1, 1, 1, 1);
+const yDist = pathBBox.y2 - pathBBox.y1;
 aPath.draw(ctx);
 const pathData: string = aPath.toPathData(7);
 const pathSvg: string = aPath.toSVG(7);