diff --git a/packages/wc/components/presentation/wc.ts b/packages/wc/components/presentation/wc.ts
index f3e6047..604f931 100644
--- a/packages/wc/components/presentation/wc.ts
+++ b/packages/wc/components/presentation/wc.ts
@@ -385,6 +385,12 @@ export class PresentationWC extends LitElement {
   }
 
   fireUpdates(entries: IntersectionObserverEntry[]) {
+    // IO drives audience-mode scroll navigation. In presenter mode the
+    // host stops scrolling and slides redistribute into named slots; the
+    // resulting flurry of intersection changes would otherwise feed
+    // bogus `navigate.scroll` events into xstate and march currentIndex
+    // through every slide before settling at the last one to fire.
+    if (this.role !== "audience") return;
     for (const entry of entries) {
       if (entry.isIntersecting) {
         this.presentation.send({