diff --git a/packages/core/src/lib/keep_alive_manager.ts b/packages/core/src/lib/keep_alive_manager.ts
index 2b3b9e6c73..2bc86efdf6 100644
--- a/packages/core/src/lib/keep_alive_manager.ts
+++ b/packages/core/src/lib/keep_alive_manager.ts
@@ -2,7 +2,7 @@ import type { PeerId } from "@libp2p/interface/peer-id";
 import type { PeerStore } from "@libp2p/interface/peer-store";
 import type { IRelay, PeerIdStr } from "@waku/interfaces";
 import type { KeepAliveOptions } from "@waku/interfaces";
-import { Logger, pubsubTopicToShardInfo } from "@waku/utils";
+import { Logger, pubsubTopicToSingleTopicShardInfo } from "@waku/utils";
 import { utf8ToBytes } from "@waku/utils/bytes";
 import type { PingService } from "libp2p/ping";
 
@@ -123,7 +123,7 @@ export class KeepAliveManager {
       if (!meshPeers.includes(peerIdStr)) continue;
 
       const encoder = createEncoder({
-        pubsubTopicShardInfo: pubsubTopicToShardInfo(topic),
+        pubsubTopicShardInfo: pubsubTopicToSingleTopicShardInfo(topic),
         contentTopic: RelayPingContentTopic,
         ephemeral: true
       });
diff --git a/packages/interfaces/src/message.ts b/packages/interfaces/src/message.ts
index aaf6ebba69..f3390ec212 100644
--- a/packages/interfaces/src/message.ts
+++ b/packages/interfaces/src/message.ts
@@ -43,7 +43,7 @@ export interface IMetaSetter {
 }
 
 export interface EncoderOptions {
-  pubsubTopic?: SingleTopicShardInfo | PubsubTopic;
+  pubsubTopicShardInfo?: SingleTopicShardInfo;
   /** The content topic to set on outgoing messages. */
   contentTopic: string;
   /**
diff --git a/packages/utils/src/common/sharding.ts b/packages/utils/src/common/sharding.ts
index 2084cd8529..c23b248ef8 100644
--- a/packages/utils/src/common/sharding.ts
+++ b/packages/utils/src/common/sharding.ts
@@ -26,22 +26,16 @@ export const shardInfoToPubsubTopics = (
   );
 };
 
-export const pubsubTopicToShardInfo = (
-  pubsubTopics: PubsubTopic[]
-): ShardInfo => {
-  const indexList: number[] = [];
-  const cluster = parseInt(pubsubTopics[0].split("/")[4]);
-  for (const topic of pubsubTopics) {
-    const topicCluster = parseInt(topic.split("/")[4]);
-    if (topicCluster !== cluster) {
-      throw new Error(
-        "Pubsub topics must be from the same cluster to convert to shard info"
-      );
-    }
-    const index = parseInt(topic.split("/")[5]);
-    indexList.push(index);
-  }
-  return { cluster, indexList };
+export const pubsubTopicToSingleTopicShardInfo = (
+  pubsubTopics: PubsubTopic
+): SingleTopicShardInfo => {
+  const parts = pubsubTopics.split("/");
+  if (parts.length != 5) throw new Error("Invalid pubsub topic");
+
+  return {
+    cluster: parseInt(parts[3]),
+    index: parseInt(parts[4])
+  };
 };
 
 export function ensurePubsubTopicIsConfigured(