diff --git a/src/lib/swipe.js b/src/lib/swipe.js
index dd5fa86..3037c5f 100644
--- a/src/lib/swipe.js
+++ b/src/lib/swipe.js
@@ -32,11 +32,19 @@ export function onSwipe(target, { onLeft, onRight, threshold = 60 } = {}) {
     const dx = e.touches[0].clientX - x0;
     const dy = e.touches[0].clientY - y0;
     if (!claimed) {
-      if (Math.abs(dy) > 12 && Math.abs(dy) > Math.abs(dx)) {
-        active = false; // it's a vertical scroll — let it be
+      const adx = Math.abs(dx);
+      const ady = Math.abs(dy);
+      // Scroll is the default: bail out — permanently — at the first sign of
+      // vertical intent, even a mildly diagonal one. A page full of scrolling
+      // content (tab panels, lists) means a fast flick's first sample is
+      // often diagonal; without this bias it gets misread as a page-swipe
+      // and the rest of the scroll gets eaten by preventDefault().
+      if (ady > 10 && ady > adx * 0.7) {
+        active = false;
         return;
       }
-      if (Math.abs(dx) > 10 && Math.abs(dx) > Math.abs(dy)) claimed = true;
+      // Only claim a horizontal page-swipe once the drag is unambiguous.
+      if (adx > 20 && adx > ady * 2) claimed = true;
     }
     if (claimed) e.preventDefault();
   };