diff --git a/apps/readest-app/src/__tests__/document/fixed-layout-pinch-zoom.test.ts b/apps/readest-app/src/__tests__/document/fixed-layout-pinch-zoom.test.ts
new file mode 100644
index 00000000..2ced5ca4
--- /dev/null
+++ b/apps/readest-app/src/__tests__/document/fixed-layout-pinch-zoom.test.ts
@@ -0,0 +1,38 @@
+import { describe, expect, it } from 'vitest';
+
+import { computeScrollPinchTransform } from 'foliate-js/fixed-layout.js';
+
+describe('computeScrollPinchTransform', () => {
+  it('scales by the pinch ratio anchored at the viewport centre in both axes', () => {
+    // Anchoring the live preview at the viewport centre (in container
+    // coordinates) matches the post-pinch re-render, which restores the same
+    // centre point via the center anchor, so the zoom does not jump on release.
+    expect(
+      computeScrollPinchTransform({
+        ratio: 1.5,
+        scrollLeft: 0,
+        scrollTop: 2000,
+        viewportWidth: 360,
+        viewportHeight: 640,
+      }),
+    ).toEqual({
+      transform: 'scale(1.5)',
+      transformOrigin: '180px 2320px',
+    });
+  });
+
+  it('offsets the origin by the current scroll position', () => {
+    expect(
+      computeScrollPinchTransform({
+        ratio: 0.8,
+        scrollLeft: 90,
+        scrollTop: 0,
+        viewportWidth: 360,
+        viewportHeight: 640,
+      }),
+    ).toEqual({
+      transform: 'scale(0.8)',
+      transformOrigin: '270px 320px',
+    });
+  });
+});
diff --git a/packages/foliate-js b/packages/foliate-js
index 6f1a1901..0fa407c4 160000
--- a/packages/foliate-js
+++ b/packages/foliate-js
@@ -1 +1 @@
-Subproject commit 6f1a190184802457f38a9e75a8111fc50e19e068
+Subproject commit 0fa407c4c63f09a5795c808503d1030231c645f0