diff --git a/src/lib/util/flag-resolver.ts b/src/lib/util/flag-resolver.ts
index dca4c99eed..453e6ea84a 100644
--- a/src/lib/util/flag-resolver.ts
+++ b/src/lib/util/flag-resolver.ts
@@ -68,7 +68,7 @@ export default class FlagResolver implements IFlagResolver {
     }
 
     get impactMetrics(): IImpactMetricsResolver | undefined {
-        return this.externalResolver.impactMetrics;
+        return this.externalResolver?.impactMetrics;
     }
 }