diff --git a/css-element-queries.d.ts b/css-element-queries.d.ts
index 97ee144..3fe0706 100644
--- a/css-element-queries.d.ts
+++ b/css-element-queries.d.ts
@@ -1,2 +1,2 @@
-export { ResizeSensor, ResizeSensorCallback } from "./src/ResizeSensor";
+export { ResizeSensor, ResizeSensorCallback, Size } from "./src/ResizeSensor";
 export { ElementQueries } from './src/ElementQueries';
\ No newline at end of file
diff --git a/src/ResizeSensor.d.ts b/src/ResizeSensor.d.ts
index ad6c412..3fba8c6 100644
--- a/src/ResizeSensor.d.ts
+++ b/src/ResizeSensor.d.ts
@@ -1,4 +1,9 @@
-export declare type ResizeSensorCallback = (size: { width: number; height: number; }) => void;
+export declare interface Size {
+    width: number;
+    height: number;
+}
+
+export declare type ResizeSensorCallback = (size: Size) => void;
 
 export declare class ResizeSensor {
     /**