diff --git a/web_src/js/features/imagediff.ts b/web_src/js/features/imagediff.ts
index 23f05fbdc7..1e89aa8b6e 100644
--- a/web_src/js/features/imagediff.ts
+++ b/web_src/js/features/imagediff.ts
@@ -53,7 +53,7 @@ function getDefaultSvgBoundsIfUndefined(text: string, src: string): Bounds | nul
       const viewBox = svg.viewBox.baseVal;
       return {
         width: defaultSize,
-        height: defaultSize * viewBox.width / viewBox.height,
+        height: defaultSize * viewBox.height / viewBox.width,
       };
     }
     return {