diff --git a/packages/types/src/primitive/Generic/ConsensusEngineId.ts b/packages/types/src/primitive/Generic/ConsensusEngineId.ts
index 36f30988cc..9f3ebf9ec3 100644
--- a/packages/types/src/primitive/Generic/ConsensusEngineId.ts
+++ b/packages/types/src/primitive/Generic/ConsensusEngineId.ts
@@ -79,10 +79,12 @@ export default class ConsensusEngineId extends U32 {
    * @description From the input bytes, decode into an author
    */
   public extractAuthor (bytes: Bytes, sessionValidators: AccountId[]): AccountId | undefined {
-    if (this.isAura) {
-      return this.getAuraAuthor(bytes, sessionValidators);
-    } else if (this.isBabe) {
-      return this.getBabeAuthor(bytes, sessionValidators);
+    if (sessionValidators?.length) {
+      if (this.isAura) {
+        return this.getAuraAuthor(bytes, sessionValidators);
+      } else if (this.isBabe) {
+        return this.getBabeAuthor(bytes, sessionValidators);
+      }
     }
 
     return undefined;