diff --git a/src/onINP.ts b/src/onINP.ts
index cf857de5..ac23c2fe 100644
--- a/src/onINP.ts
+++ b/src/onINP.ts
@@ -220,7 +220,10 @@ export const onINP = (onReport: INPReportCallback, opts?: ReportOpts) => {
       // If browser supports interactionId (and so supports INP), also
       // observe entries of type `first-input`. This is useful in cases
       // where the first interaction is less than the `durationThreshold`.
-      if ('interactionId' in PerformanceEventTiming.prototype) {
+      if (
+        'PerformanceEventTiming' in window &&
+        'interactionId' in PerformanceEventTiming.prototype
+      ) {
         po.observe({type: 'first-input', buffered: true});
       }