diff --git a/web/firefoxcom.js b/web/firefoxcom.js
index 06b5f1b194db0..e8265df723dab 100644
--- a/web/firefoxcom.js
+++ b/web/firefoxcom.js
@@ -400,6 +400,9 @@ class ExternalServices extends BaseExternalServices {
   }
 
   async getNimbusExperimentData() {
+    if (typeof PDFJSDev === "undefined" || !PDFJSDev.test("GECKOVIEW")) {
+      return null;
+    }
     const nimbusData = await FirefoxCom.requestAsync(
       "getNimbusExperimentData",
       null