diff --git a/platform/telemetry/src/TelemetrySubscription.js b/platform/telemetry/src/TelemetrySubscription.js
index 5e929d8ee4..c8d3914726 100644
--- a/platform/telemetry/src/TelemetrySubscription.js
+++ b/platform/telemetry/src/TelemetrySubscription.js
@@ -58,7 +58,10 @@ define(
             // Invoke the observer callback to notify that new streaming
             // data has become available.
             function fireCallback() {
-                callback();
+                // Fire callback, if one was provided
+                if (callback) {
+                    callback();
+                }
                 // Clear the pending flag so that future updates will
                 // schedule this callback.
                 updatePending = false;