diff --git a/src/library/controller.js b/src/library/controller.js
index b90654c7b..9e2807e4a 100644
--- a/src/library/controller.js
+++ b/src/library/controller.js
@@ -204,7 +204,12 @@ export function createDataLibrary({
       if (wanted && !register(entry)) continue;
       if (!isRegistered(id)) continue;
       const layerId = libraryLayerId(id);
-      if (wanted === (dataManager.isEnabled?.(layerId) === true)) continue;
+      // Compare with the newest request, not settled state: a layer still
+      // switching on for an earlier share must be switched off by this one.
+      const current =
+        dataManager.isEffectivelyEnabled?.(layerId) ??
+        dataManager.isEnabled?.(layerId);
+      if (wanted === (current === true)) continue;
       dataManager
         .setEnabled(layerId, wanted, { origin })
         .catch((error) =>
diff --git a/src/library/controller.test.mjs b/src/library/controller.test.mjs
index 53e553233..4b75e7b91 100644
--- a/src/library/controller.test.mjs
+++ b/src/library/controller.test.mjs
@@ -316,6 +316,35 @@ test('navigating between shares switches library entries on and off', async (t)
   assert.equal(shareLink.listener, null);
 });
 
+test('a share opened while an earlier one is still switching on wins', async (t) => {
+  const manager = sealedManager(t);
+  const shareLink = fakeShareLink(null);
+  const library = createDataLibrary({
+    entries,
+    ledger,
+    dataManager: manager,
+    services: {},
+    storage: memoryStorage(),
+    shareLink,
+    source: source({}),
+  });
+  await library.start();
+  const settle = () =>
+    Promise.all(
+      ['lib-night-lights', 'lib-sea-marks'].map((id) =>
+        manager.waitForLayerSettled?.(id),
+      ),
+    );
+  // Neither share waits for the one before it to settle.
+  shareLink.listener(['00']);
+  assert.equal(manager.isEnabled('lib-night-lights'), false, 'still enabling');
+  shareLink.listener(['01']);
+  await settle();
+  assert.equal(manager.isEnabled('lib-night-lights'), false);
+  assert.equal(manager.isEnabled('lib-sea-marks'), true);
+  library.destroy();
+});
+
 test('zoom flies to an added layer through the caller, reset removes everything', async (t) => {
   const manager = sealedManager(t);
   const storage = memoryStorage();