diff --git a/packages/core/src/lib/message/version_0.spec.ts b/packages/core/src/lib/message/version_0.spec.ts
index 4ee67ff165..7498c15f80 100644
--- a/packages/core/src/lib/message/version_0.spec.ts
+++ b/packages/core/src/lib/message/version_0.spec.ts
@@ -137,3 +137,27 @@ describe("Ensures content topic is defined", () => {
     expect(wrapper).to.throw("Content topic must be specified");
   });
 });
+
+describe("Sets sharding configuration correctly", () => {
+  it("uses static shard pubsub topic instead of autosharding when set", async () => {
+    // Create an encoder setup to use autosharding
+    const ContentTopic = "/waku/2/content/test.js";
+    const autoshardingEncoder = createEncoder({
+      pubsubTopicShardInfo: { clusterId: 0 },
+      contentTopic: ContentTopic
+    });
+
+    // When autosharding is enabled, we expect the shard index to be 1
+    expect(autoshardingEncoder.pubsubTopic).to.be.eq("/waku/2/rs/0/1");
+
+    // Create an encoder setup to use static sharding with the same content topic
+    const singleShardInfo = { clusterId: 0, shard: 0 };
+    const staticshardingEncoder = createEncoder({
+      contentTopic: ContentTopic,
+      pubsubTopicShardInfo: singleShardInfo
+    });
+
+    // When static sharding is enabled, we expect the shard index to be 0
+    expect(staticshardingEncoder.pubsubTopic).to.be.eq("/waku/2/rs/0/0");
+  });
+});
diff --git a/packages/interfaces/src/message.ts b/packages/interfaces/src/message.ts
index 1e48030288..1c8348239e 100644
--- a/packages/interfaces/src/message.ts
+++ b/packages/interfaces/src/message.ts
@@ -5,7 +5,7 @@ export interface SingleShardInfo {
   /**
    * Specifying this field indicates to the encoder/decoder that static sharding must be used.
    */
-  shard: number;
+  shard?: number;
 }
 
 export interface IRateLimitProof {
diff --git a/packages/utils/src/common/sharding.spec.ts b/packages/utils/src/common/sharding.spec.ts
index 7ae9f2bc18..cc5ea223ca 100644
--- a/packages/utils/src/common/sharding.spec.ts
+++ b/packages/utils/src/common/sharding.spec.ts
@@ -409,7 +409,7 @@ describe("determinePubsubTopic", () => {
 
   it("should process correctly when SingleShardInfo has no clusterId but has a shard", () => {
     const info = { shard: 0 };
-    const expectedTopic = `/waku/2/rs/${DEFAULT_CLUSTER_ID}/6`;
+    const expectedTopic = `/waku/2/rs/${DEFAULT_CLUSTER_ID}/0`;
     expect(determinePubsubTopic(contentTopic, info as any)).to.equal(
       expectedTopic
     );
diff --git a/packages/utils/src/common/sharding.ts b/packages/utils/src/common/sharding.ts
index 6d9a98f540..79be1e6d36 100644
--- a/packages/utils/src/common/sharding.ts
+++ b/packages/utils/src/common/sharding.ts
@@ -13,10 +13,9 @@ import { concat, utf8ToBytes } from "../bytes/index.js";
 export const singleShardInfoToPubsubTopic = (
   shardInfo: SingleShardInfo
 ): PubsubTopic => {
-  if (shardInfo.clusterId === undefined || shardInfo.shard === undefined)
-    throw new Error("Invalid shard");
+  if (shardInfo.shard === undefined) throw new Error("Invalid shard");
 
-  return `/waku/2/rs/${shardInfo.clusterId}/${shardInfo.shard}`;
+  return `/waku/2/rs/${shardInfo.clusterId ?? DEFAULT_CLUSTER_ID}/${shardInfo.shard}`;
 };
 
 export const singleShardInfosToShardInfo = (
@@ -232,7 +231,7 @@ export function determinePubsubTopic(
     return pubsubTopicShardInfo;
   } else {
     return pubsubTopicShardInfo
-      ? pubsubTopicShardInfo.shard
+      ? pubsubTopicShardInfo.shard !== undefined
         ? singleShardInfoToPubsubTopic(pubsubTopicShardInfo)
         : contentTopicToPubsubTopic(
             contentTopic,
@@ -301,7 +300,7 @@ export const ensureShardingConfigured = (
       shardingParams: { clusterId, application, version },
       shardInfo: {
         clusterId,
-        shards: [pubsubTopicToSingleShardInfo(pubsubTopic).shard]
+        shards: [pubsubTopicToSingleShardInfo(pubsubTopic).shard!]
       },
       pubsubTopics: [pubsubTopic]
     };