diff --git a/apps/wakunode2/app.nim b/apps/wakunode2/app.nim
index d7c1482502..2bdf4cf708 100644
--- a/apps/wakunode2/app.nim
+++ b/apps/wakunode2/app.nim
@@ -128,23 +128,19 @@ proc init*(T: type App, rng: ref HmacDrbgContext, conf: WakuNodeConf): T =
 
   enrBuilder.withMultiaddrs(netConfig.enrMultiaddrs)
 
-  let contentTopicsRes = conf.contentTopics.mapIt(NsContentTopic.parse(it))
+  let topics =
+    if conf.pubsubTopics.len > 0 or conf.contentTopics.len > 0:
+      let shardsRes = conf.contentTopics.mapIt(getShard(it))
+      for res in shardsRes:
+        if res.isErr():
+          error "failed to shard content topic", error=res.error
+          quit(QuitFailure)
 
-  for res in contentTopicsRes:
-    if res.isErr():
-      error "failed to parse content topic", error=res.error
-      quit(QuitFailure)
-
-  let shardsRes = contentTopicsRes.mapIt(getShard(it.get()))
+      let shards = shardsRes.mapIt(it.get())
 
-  for res in shardsRes:
-    if res.isErr():
-      error "failed to shard content topic", error=res.error
-      quit(QuitFailure)
-
-  let shards = shardsRes.mapIt($it.get())
-
-  let topics = conf.topics & conf.pubsubTopics & shards
+      conf.pubsubTopics & shards
+    else:
+      conf.topics
 
   let addShardedTopics = enrBuilder.withShardedTopics(topics)
   if addShardedTopics.isErr():
@@ -360,12 +356,15 @@ proc setupProtocols(node: WakuNode,
     peerExchangeHandler = some(handlePeerExchange)
 
   if conf.relay:
-    # TODO autoshard content topics only once.
-    # Already checked for errors in app.init
-    let contentTopics = conf.contentTopics.mapIt(NsContentTopic.parse(it).expect("Parsing"))
-    let shards = contentTopics.mapIt($(getShard(it).expect("Sharding")))
+    let pubsubTopics =
+      if conf.pubsubTopics.len > 0 or conf.contentTopics.len > 0:
+        # TODO autoshard content topics only once.
+        # Already checked for errors in app.init
+        let shards = conf.contentTopics.mapIt(getShard(it).expect("Valid Shard"))
+        conf.pubsubTopics & shards
+      else:
+        conf.topics
 
-    let pubsubTopics = conf.topics & conf.pubsubTopics & shards
     try:
       await mountRelay(node, pubsubTopics, peerExchangeHandler = peerExchangeHandler)
     except CatchableError:
diff --git a/waku/waku_core/topics/sharding.nim b/waku/waku_core/topics/sharding.nim
index ddcdba0a38..f616f54b72 100644
--- a/waku/waku_core/topics/sharding.nim
+++ b/waku/waku_core/topics/sharding.nim
@@ -47,6 +47,14 @@ proc getShard*(topic: NsContentTopic): Result[NsPubsubTopic, string] =
     of 0: return ok(getGenZeroShard(topic, GenerationZeroShardsCount))
     else: return err("Generation > 0 are not supported yet")
 
+proc getShard*(topic: ContentTopic): Result[PubsubTopic, string] =
+  let parsedTopic = NsContentTopic.parse(topic).valueOr:
+    return err($error)
+
+  let shard = ?getShard(parsedTopic)
+
+  ok($shard)
+
 proc parseSharding*(pubsubTopic: Option[PubsubTopic], contentTopics: ContentTopic|seq[ContentTopic]): Result[Table[NsPubsubTopic, seq[NsContentTopic]], string] =
   var topics: seq[ContentTopic]
   when contentTopics is seq[ContentTopic]: