diff --git a/src/lib/layout/Gutter.tsx b/src/lib/layout/Gutter.tsx
index 30e9e16..b0c28a8 100644
--- a/src/lib/layout/Gutter.tsx
+++ b/src/lib/layout/Gutter.tsx
@@ -18,7 +18,9 @@ import { type Box, type GutterInfo, MIN_PANE_PX } from "./tree";
  * On release while armed, `onPromote` fires.
  */
 const HITBOX_PX = 8;
-const PROMOTE_TRIGGER_FRAC = 0.75;
+/** Cursor must reach this fraction across the sibling pane (in the exit
+ *  direction) to arm the promote gesture. 0.5 = middle of the sibling. */
+const PROMOTE_TRIGGER_FRAC = 0.5;
 
 export default function Gutter({
   info,