diff --git a/libp2p/multistream.nim b/libp2p/multistream.nim
index f9b0e0c0c..1221c2ec1 100644
--- a/libp2p/multistream.nim
+++ b/libp2p/multistream.nim
@@ -7,8 +7,8 @@
 ## This file may not be copied, modified, or distributed except according to
 ## those terms.
 
-import strutils, stew/byteutils
-import chronos, chronicles
+import strutils
+import chronos, chronicles, stew/byteutils
 import connection,
        vbuffer,
        errors,
@@ -58,7 +58,7 @@ proc select*(m: MultistreamSelect,
     trace "selecting proto", proto = proto
     await conn.writeLp((proto[0] & "\n")) # select proto
 
-  result = cast[string]((await conn.readLp(1024))) # read ms header
+  result = string.fromBytes((await conn.readLp(1024))) # read ms header
   result.removeSuffix("\n")
   if result != Codec:
     notice "handshake failed", codec = result.toHex()
diff --git a/libp2p/muxers/mplex/coder.nim b/libp2p/muxers/mplex/coder.nim
index 9df47e954..850b177bb 100644
--- a/libp2p/muxers/mplex/coder.nim
+++ b/libp2p/muxers/mplex/coder.nim
@@ -8,7 +8,7 @@
 ## those terms.
 
 import chronos
-import nimcrypto/utils, chronicles
+import nimcrypto/utils, chronicles, stew/byteutils
 import types,
        ../../connection,
        ../../utility,
@@ -74,7 +74,7 @@ proc writeMsg*(conn: Connection,
                msgType: MessageType,
                data: string) {.async, gcsafe.} =
   # TODO: changing this to
-  #`await conn.writeMsg(id, msgType, cast[seq[byte]](data))`
+  #`await conn.writeMsg(id, msgType, data.toBytes())`
   # causes all sorts of race conditions and hangs.
   # DON'T DO IT!
-  result = conn.writeMsg(id, msgType, cast[seq[byte]](data))
+  result = conn.writeMsg(id, msgType, data.toBytes())
diff --git a/libp2p/muxers/mplex/mplex.nim b/libp2p/muxers/mplex/mplex.nim
index 6dd53b5b7..d4b21120b 100644
--- a/libp2p/muxers/mplex/mplex.nim
+++ b/libp2p/muxers/mplex/mplex.nim
@@ -8,7 +8,7 @@
 ## those terms.
 
 import tables, sequtils, oids
-import chronos, chronicles
+import chronos, chronicles, stew/byteutils
 import ../muxer,
        ../../connection,
        ../../stream/lpstream,
@@ -89,7 +89,7 @@ method handle*(m: Mplex) {.async, gcsafe.} =
 
         case msgType:
           of MessageType.New:
-            let name = cast[string](data)
+            let name = string.fromBytes(data)
             channel = await m.newStreamInternal(false, id, name)
             trace "created channel", id = id,
                                     name = name,
diff --git a/libp2p/protocols/pubsub/rpc/message.nim b/libp2p/protocols/pubsub/rpc/message.nim
index cc5103b24..ba16dc275 100644
--- a/libp2p/protocols/pubsub/rpc/message.nim
+++ b/libp2p/protocols/pubsub/rpc/message.nim
@@ -8,7 +8,7 @@
 ## those terms.
 
 import options
-import chronicles
+import chronicles, stew/byteutils
 import nimcrypto/sysrand
 import messages, protobuf,
        ../../../peer,
@@ -23,7 +23,7 @@ const PubSubPrefix = "libp2p-pubsub:"
 
 proc msgIdProvider(m: Message): string =
   ## default msg id provider
-  m.seqno.toHex() & PeerID.init(m.fromPeer).pretty
+  crypto.toHex(m.seqno) & PeerID.init(m.fromPeer).pretty
 
 template msgId*(m: Message): string =
   ## calls the ``msgIdProvider`` from
@@ -41,7 +41,7 @@ proc sign*(msg: Message, p: PeerInfo): Message {.gcsafe.} =
   if buff.buffer.len > 0:
     result = msg
     result.signature = p.privateKey.
-                       sign(cast[seq[byte]](PubSubPrefix) & buff.buffer).tryGet().
+                       sign(PubSubPrefix.toBytes() & buff.buffer).tryGet().
                        getBytes()
 
 proc verify*(m: Message, p: PeerInfo): bool =
@@ -57,7 +57,7 @@ proc verify*(m: Message, p: PeerInfo): bool =
     var key: PublicKey
     if remote.init(m.signature) and key.init(m.key):
       trace "verifying signature", remoteSignature = remote
-      result = remote.verify(cast[seq[byte]](PubSubPrefix) & buff.buffer, key)
+      result = remote.verify(PubSubPrefix.toBytes() & buff.buffer, key)
 
 proc newMessage*(p: PeerInfo,
                  data: seq[byte],
diff --git a/tests/pubsub/testfloodsub.nim b/tests/pubsub/testfloodsub.nim
index 169917a6d..583787333 100644
--- a/tests/pubsub/testfloodsub.nim
+++ b/tests/pubsub/testfloodsub.nim
@@ -10,7 +10,7 @@
 {.used.}
 
 import unittest, sequtils, options, tables, sets
-import chronos
+import chronos, stew/byteutils
 import utils,
        ../../libp2p/[errors,
                      switch,
@@ -60,7 +60,7 @@ suite "FloodSub":
       await nodes[1].subscribe("foobar", handler)
       await waitSub(nodes[0], nodes[1], "foobar")
 
-      await nodes[0].publish("foobar", cast[seq[byte]]("Hello!"))
+      await nodes[0].publish("foobar", "Hello!".toBytes())
 
       result = await completionFut.wait(5.seconds)
 
@@ -91,7 +91,7 @@ suite "FloodSub":
       await nodes[0].subscribe("foobar", handler)
       await waitSub(nodes[1], nodes[0], "foobar")
 
-      await nodes[1].publish("foobar", cast[seq[byte]]("Hello!"))
+      await nodes[1].publish("foobar", "Hello!".toBytes())
 
       result = await completionFut.wait(5.seconds)
 
@@ -126,7 +126,7 @@ suite "FloodSub":
 
       nodes[1].addValidator("foobar", validator)
 
-      await nodes[0].publish("foobar", cast[seq[byte]]("Hello!"))
+      await nodes[0].publish("foobar", "Hello!".toBytes())
 
       check (await handlerFut) == true
       await allFuturesThrowing(
@@ -160,7 +160,7 @@ suite "FloodSub":
 
       nodes[1].addValidator("foobar", validator)
 
-      await nodes[0].publish("foobar", cast[seq[byte]]("Hello!"))
+      await nodes[0].publish("foobar", "Hello!".toBytes())
 
       await allFuturesThrowing(
         nodes[0].stop(),
@@ -198,8 +198,8 @@ suite "FloodSub":
 
       nodes[1].addValidator("foo", "bar", validator)
 
-      await nodes[0].publish("foo", cast[seq[byte]]("Hello!"))
-      await nodes[0].publish("bar", cast[seq[byte]]("Hello!"))
+      await nodes[0].publish("foo", "Hello!".toBytes())
+      await nodes[0].publish("bar", "Hello!".toBytes())
 
       await allFuturesThrowing(
         nodes[0].stop(),
@@ -252,7 +252,7 @@ suite "FloodSub":
 
       var pubs: seq[Future[void]]
       for i in 0..<runs:
-        pubs &= nodes[i].publish("foobar", cast[seq[byte]]("Hello!"))
+        pubs &= nodes[i].publish("foobar", "Hello!".toBytes())
       await allFuturesThrowing(pubs)
 
       await allFuturesThrowing(futs.mapIt(it[0]))
@@ -306,7 +306,7 @@ suite "FloodSub":
 
       var pubs: seq[Future[void]]
       for i in 0..<runs:
-        pubs &= nodes[i].publish("foobar", cast[seq[byte]]("Hello!"))
+        pubs &= nodes[i].publish("foobar", "Hello!".toBytes())
       await allFuturesThrowing(pubs)
 
       await allFuturesThrowing(futs.mapIt(it[0]))
diff --git a/tests/pubsub/testgossipsub.nim b/tests/pubsub/testgossipsub.nim
index e32c218a7..dc57daacc 100644
--- a/tests/pubsub/testgossipsub.nim
+++ b/tests/pubsub/testgossipsub.nim
@@ -10,7 +10,7 @@
 {.used.}
 
 import unittest, sequtils, options, tables, sets
-import chronos
+import chronos, stew/byteutils
 import chronicles
 import utils, ../../libp2p/[errors,
                             peer,
@@ -76,7 +76,7 @@ suite "GossipSub":
         result = true
 
       nodes[1].addValidator("foobar", validator)
-      await nodes[0].publish("foobar", cast[seq[byte]]("Hello!"))
+      await nodes[0].publish("foobar", "Hello!".toBytes())
 
       result = (await validatorFut) and (await handlerFut)
       await allFuturesThrowing(
@@ -110,7 +110,7 @@ suite "GossipSub":
         result = false
 
       nodes[1].addValidator("foobar", validator)
-      await nodes[0].publish("foobar", cast[seq[byte]]("Hello!"))
+      await nodes[0].publish("foobar", "Hello!".toBytes())
 
       result = await validatorFut
       await allFuturesThrowing(
@@ -151,8 +151,8 @@ suite "GossipSub":
           false
 
       nodes[1].addValidator("foo", "bar", validator)
-      await nodes[0].publish("foo", cast[seq[byte]]("Hello!"))
-      await nodes[0].publish("bar", cast[seq[byte]]("Hello!"))
+      await nodes[0].publish("foo", "Hello!".toBytes())
+      await nodes[0].publish("bar", "Hello!".toBytes())
 
       result = ((await passed) and (await failed) and (await handlerFut))
       await allFuturesThrowing(
@@ -272,7 +272,7 @@ suite "GossipSub":
       nodes[1].pubsub.get().addObserver(obs1)
       nodes[0].pubsub.get().addObserver(obs2)
 
-      await nodes[0].publish("foobar", cast[seq[byte]]("Hello!"))
+      await nodes[0].publish("foobar", "Hello!".toBytes())
 
       var gossipSub1: GossipSub = GossipSub(nodes[0].pubSub.get())
 
@@ -309,7 +309,7 @@ suite "GossipSub":
       await nodes[1].subscribe("foobar", handler)
       await waitSub(nodes[0], nodes[1], "foobar")
 
-      await nodes[0].publish("foobar", cast[seq[byte]]("Hello!"))
+      await nodes[0].publish("foobar", "Hello!".toBytes())
 
       result = await passed
 
diff --git a/tests/pubsub/testmcache.nim b/tests/pubsub/testmcache.nim
index a1f1655a4..fca0011ec 100644
--- a/tests/pubsub/testmcache.nim
+++ b/tests/pubsub/testmcache.nim
@@ -1,7 +1,7 @@
 {.used.}
 
-import options, sets, sequtils
-import unittest
+import unittest, options, sets, sequtils
+import stew/byteutils
 import ../../libp2p/[peer,
                      crypto/crypto,
                      protocols/pubsub/mcache,
@@ -12,7 +12,7 @@ suite "MCache":
   test "put/get":
     var mCache = newMCache(3, 5)
     var msg = Message(fromPeer: PeerID.init(PrivateKey.random(ECDSA).get()).data,
-                       seqno: cast[seq[byte]]("12345"))
+                       seqno: "12345".toBytes())
     mCache.put(msg)
     check mCache.get(msg.msgId).isSome and mCache.get(msg.msgId).get() == msg
 
@@ -21,13 +21,13 @@ suite "MCache":
 
     for i in 0..<3:
       var msg = Message(fromPeer: PeerID.init(PrivateKey.random(ECDSA).get()).data,
-                        seqno: cast[seq[byte]]("12345"),
+                        seqno: "12345".toBytes(),
                         topicIDs: @["foo"])
       mCache.put(msg)
 
     for i in 0..<5:
       var msg = Message(fromPeer: PeerID.init(PrivateKey.random(ECDSA).get()).data,
-                        seqno: cast[seq[byte]]("12345"),
+                        seqno: "12345".toBytes(),
                         topicIDs: @["bar"])
       mCache.put(msg)
 
@@ -42,7 +42,7 @@ suite "MCache":
 
     for i in 0..<3:
       var msg = Message(fromPeer: PeerID.init(PrivateKey.random(ECDSA).get()).data,
-                        seqno: cast[seq[byte]]("12345"),
+                        seqno: "12345".toBytes(),
                         topicIDs: @["foo"])
       mCache.put(msg)
 
@@ -51,7 +51,7 @@ suite "MCache":
 
     for i in 0..<3:
       var msg = Message(fromPeer: PeerID.init(PrivateKey.random(ECDSA).get()).data,
-                        seqno: cast[seq[byte]]("12345"),
+                        seqno: "12345".toBytes(),
                         topicIDs: @["bar"])
       mCache.put(msg)
 
@@ -60,7 +60,7 @@ suite "MCache":
 
     for i in 0..<3:
       var msg = Message(fromPeer: PeerID.init(PrivateKey.random(ECDSA).get()).data,
-                        seqno: cast[seq[byte]]("12345"),
+                        seqno: "12345".toBytes(),
                         topicIDs: @["baz"])
       mCache.put(msg)
 
@@ -72,19 +72,19 @@ suite "MCache":
 
     for i in 0..<3:
       var msg = Message(fromPeer: PeerID.init(PrivateKey.random(ECDSA).get()).data,
-                        seqno: cast[seq[byte]]("12345"),
+                        seqno: "12345".toBytes(),
                         topicIDs: @["foo"])
       mCache.put(msg)
 
     for i in 0..<3:
       var msg = Message(fromPeer: PeerID.init(PrivateKey.random(ECDSA).get()).data,
-                        seqno: cast[seq[byte]]("12345"),
+                        seqno: "12345".toBytes(),
                         topicIDs: @["bar"])
       mCache.put(msg)
 
     for i in 0..<3:
       var msg = Message(fromPeer: PeerID.init(PrivateKey.random(ECDSA).get()).data,
-                        seqno: cast[seq[byte]]("12345"),
+                        seqno: "12345".toBytes(),
                         topicIDs: @["baz"])
       mCache.put(msg)
 
diff --git a/tests/testbufferstream.nim b/tests/testbufferstream.nim
index e8d6e3821..98b8f339a 100644
--- a/tests/testbufferstream.nim
+++ b/tests/testbufferstream.nim
@@ -1,5 +1,5 @@
 import unittest, strformat
-import chronos
+import chronos, stew/byteutils
 import ../libp2p/errors
 import ../libp2p/stream/bufferstream
 
@@ -15,9 +15,8 @@ suite "BufferStream":
       proc writeHandler(data: seq[byte]) {.async, gcsafe.} = discard
       let buff = newBufferStream(writeHandler, 16)
       check buff.len == 0
-      var data: seq[char]
-      data.add(@"12345")
-      await buff.pushTo(cast[seq[byte]](data))
+      var data = "12345"
+      await buff.pushTo(data.toBytes())
       check buff.len == 5
       result = true
 
@@ -32,7 +31,7 @@ suite "BufferStream":
       let buff = newBufferStream(writeHandler, 4)
       check buff.len == 0
 
-      let fut = buff.pushTo(cast[seq[byte]](@"12345"))
+      let fut = buff.pushTo("12345".toBytes())
       check buff.len == 4
       check buff.popFirst() == byte(ord('1'))
       await fut
@@ -51,10 +50,10 @@ suite "BufferStream":
       let buff = newBufferStream(writeHandler, 10)
       check buff.len == 0
 
-      await buff.pushTo(cast[seq[byte]](@"12345"))
+      await buff.pushTo("12345".toBytes())
       var data = newSeq[byte](3)
       await buff.readExactly(addr data[0], 3)
-      check ['1', '2', '3'] == cast[string](data)
+      check ['1', '2', '3'] == string.fromBytes(data)
 
       result = true
 
@@ -69,11 +68,11 @@ suite "BufferStream":
       let buff = newBufferStream(writeHandler, 10)
       check buff.len == 0
 
-      await buff.pushTo(cast[seq[byte]](@"12345"))
+      await buff.pushTo("12345".toBytes())
       check buff.len == 5
       var data: seq[byte] = newSeq[byte](2)
       await buff.readExactly(addr data[0], 2)
-      check cast[string](data) == @['1', '2']
+      check string.fromBytes(data) == @['1', '2']
 
       result = true
 
@@ -90,11 +89,11 @@ suite "BufferStream":
 
       var data: seq[byte] = newSeq[byte](3)
       let readFut = buff.readOnce(addr data[0], 5)
-      await buff.pushTo(cast[seq[byte]](@"123"))
+      await buff.pushTo("123".toBytes())
       check buff.len == 3
 
       check (await readFut) == 3
-      check cast[string](data) == @['1', '2', '3']
+      check string.fromBytes(data) == @['1', '2', '3']
 
       result = true
 
@@ -106,7 +105,7 @@ suite "BufferStream":
   test "write ptr":
     proc testWritePtr(): Future[bool] {.async.} =
       proc writeHandler(data: seq[byte]) {.async, gcsafe.} =
-        check cast[string](data) == "Hello!"
+        check string.fromBytes(data) == "Hello!"
 
       let buff = newBufferStream(writeHandler, 10)
       check buff.len == 0
@@ -124,7 +123,7 @@ suite "BufferStream":
   test "write string":
     proc testWritePtr(): Future[bool] {.async.} =
       proc writeHandler(data: seq[byte]) {.async, gcsafe.} =
-        check cast[string](data) == "Hello!"
+        check string.fromBytes(data) == "Hello!"
 
       let buff = newBufferStream(writeHandler, 10)
       check buff.len == 0
@@ -141,12 +140,12 @@ suite "BufferStream":
   test "write bytes":
     proc testWritePtr(): Future[bool] {.async.} =
       proc writeHandler(data: seq[byte]) {.async, gcsafe.} =
-        check cast[string](data) == "Hello!"
+        check string.fromBytes(data) == "Hello!"
 
       let buff = newBufferStream(writeHandler, 10)
       check buff.len == 0
 
-      await buff.write(cast[seq[byte]]("Hello!"))
+      await buff.write("Hello!".toBytes())
 
       result = true
 
@@ -159,7 +158,7 @@ suite "BufferStream":
     proc testWritePtr(): Future[bool] {.async.} =
       var count = 1
       proc writeHandler(data: seq[byte]) {.async, gcsafe.} =
-        check cast[string](data) == &"Msg {$count}"
+        check string.fromBytes(data) == &"Msg {$count}"
         count.inc
 
       let buff = newBufferStream(writeHandler, 10)
@@ -189,32 +188,32 @@ suite "BufferStream":
       let buff = newBufferStream(writeHandler, 10)
       check buff.len == 0
 
-      await buff.pushTo(cast[seq[byte]]("Msg 1"))
-      await buff.pushTo(cast[seq[byte]]("Msg 2"))
-      await buff.pushTo(cast[seq[byte]]("Msg 3"))
+      await buff.pushTo("Msg 1".toBytes())
+      await buff.pushTo("Msg 2".toBytes())
+      await buff.pushTo("Msg 3".toBytes())
 
       var data = newSeq[byte](5)
       await buff.readExactly(addr data[0], 5)
-      check cast[string](data) == "Msg 1"
+      check string.fromBytes(data) == "Msg 1"
 
       await buff.readExactly(addr data[0], 5)
-      check cast[string](data) == "Msg 2"
+      check string.fromBytes(data) == "Msg 2"
 
       await buff.readExactly(addr data[0], 5)
-      check cast[string](data) == "Msg 3"
+      check string.fromBytes(data) == "Msg 3"
 
-      await buff.pushTo(cast[seq[byte]]("Msg 4"))
-      await buff.pushTo(cast[seq[byte]]("Msg 5"))
-      await buff.pushTo(cast[seq[byte]]("Msg 6"))
+      await buff.pushTo("Msg 4".toBytes())
+      await buff.pushTo("Msg 5".toBytes())
+      await buff.pushTo("Msg 6".toBytes())
 
       await buff.readExactly(addr data[0], 5)
-      check cast[string](data) == "Msg 4"
+      check string.fromBytes(data) == "Msg 4"
 
       await buff.readExactly(addr data[0], 5)
-      check cast[string](data) == "Msg 5"
+      check string.fromBytes(data) == "Msg 5"
 
       await buff.readExactly(addr data[0], 5)
-      check cast[string](data) == "Msg 6"
+      check string.fromBytes(data) == "Msg 6"
 
       result = true
 
@@ -232,12 +231,12 @@ suite "BufferStream":
       var buf2 = newBufferStream(writeHandler2)
 
       proc writeHandler1(data: seq[byte]) {.async, gcsafe.} =
-        var msg = cast[string](data)
+        var msg = string.fromBytes(data)
         check  msg == "Hello!"
         await buf2.pushTo(data)
 
       proc writeHandler2(data: seq[byte]) {.async, gcsafe.} =
-        var msg = cast[string](data)
+        var msg = string.fromBytes(data)
         check  msg == "Hello!"
         await buf1.pushTo(data)
 
@@ -247,14 +246,14 @@ suite "BufferStream":
       var res2: seq[byte] = newSeq[byte](7)
       var readFut2 = buf2.readExactly(addr res2[0], 7)
 
-      await buf1.pushTo(cast[seq[byte]]("Hello2!"))
-      await buf2.pushTo(cast[seq[byte]]("Hello1!"))
+      await buf1.pushTo("Hello2!".toBytes())
+      await buf2.pushTo("Hello1!".toBytes())
 
       await allFuturesThrowing(readFut1, readFut2)
 
       check:
-        res1 == cast[seq[byte]]("Hello2!")
-        res2 == cast[seq[byte]]("Hello1!")
+        res1 == "Hello2!".toBytes()
+        res2 == "Hello1!".toBytes()
 
       result = true
 
@@ -271,11 +270,11 @@ suite "BufferStream":
 
       var res1: seq[byte] = newSeq[byte](7)
       var readFut = buf2.readExactly(addr res1[0], 7)
-      await buf1.write(cast[seq[byte]]("Hello1!"))
+      await buf1.write("Hello1!".toBytes())
       await readFut
 
       check:
-        res1 == cast[seq[byte]]("Hello1!")
+        res1 == "Hello1!".toBytes()
 
       result = true
 
@@ -298,13 +297,13 @@ suite "BufferStream":
       var res2: seq[byte] = newSeq[byte](7)
       var readFut2 = buf2.readExactly(addr res2[0], 7)
 
-      await buf1.write(cast[seq[byte]]("Hello1!"))
-      await buf2.write(cast[seq[byte]]("Hello2!"))
+      await buf1.write("Hello1!".toBytes())
+      await buf2.write("Hello2!".toBytes())
       await allFuturesThrowing(readFut1, readFut2)
 
       check:
-        res1 == cast[seq[byte]]("Hello2!")
-        res2 == cast[seq[byte]]("Hello1!")
+        res1 == "Hello2!".toBytes()
+        res2 == "Hello1!".toBytes()
 
       result = true
 
@@ -324,14 +323,14 @@ suite "BufferStream":
         result = newSeq[byte](6)
         await buf1.readExactly(addr result[0], 6)
 
-      proc writer(): Future[void] = buf1.write(cast[seq[byte]]("Hello!"))
+      proc writer(): Future[void] = buf1.write("Hello!".toBytes())
 
       var writerFut = writer()
       var readerFut = reader()
 
       await writerFut
       check:
-        (await readerFut) == cast[seq[byte]]("Hello!")
+        (await readerFut) == "Hello!".toBytes()
 
       result = true
 
@@ -347,11 +346,11 @@ suite "BufferStream":
 
       var res1: seq[byte] = newSeq[byte](7)
       var readFut = buf2.readExactly(addr res1[0], 7)
-      await buf1.write(cast[seq[byte]]("Hello1!"))
+      await buf1.write("Hello1!".toBytes())
       await readFut
 
       check:
-        res1 == cast[seq[byte]]("Hello1!")
+        res1 == "Hello1!".toBytes()
 
       result = true
 
@@ -374,13 +373,13 @@ suite "BufferStream":
       var res2: seq[byte] = newSeq[byte](7)
       var readFut2 = buf2.readExactly(addr res2[0], 7)
 
-      await buf1.write(cast[seq[byte]]("Hello1!"))
-      await buf2.write(cast[seq[byte]]("Hello2!"))
+      await buf1.write("Hello1!".toBytes())
+      await buf2.write("Hello2!".toBytes())
       await allFuturesThrowing(readFut1, readFut2)
 
       check:
-        res1 == cast[seq[byte]]("Hello2!")
-        res2 == cast[seq[byte]]("Hello1!")
+        res1 == "Hello2!".toBytes()
+        res2 == "Hello1!".toBytes()
 
       result = true
 
@@ -400,14 +399,14 @@ suite "BufferStream":
         result = newSeq[byte](6)
         await buf1.readExactly(addr result[0], 6)
 
-      proc writer(): Future[void] = buf1.write(cast[seq[byte]]("Hello!"))
+      proc writer(): Future[void] = buf1.write("Hello!".toBytes())
 
       var writerFut = writer()
       var readerFut = reader()
 
       await writerFut
       check:
-        (await readerFut) == cast[seq[byte]]("Hello!")
+        (await readerFut) == "Hello!".toBytes()
 
       result = true
 
@@ -431,7 +430,7 @@ suite "BufferStream":
 
       proc writer() {.async.} =
         while count > 0:
-          await buf1.write(cast[seq[byte]]("Hello2!"))
+          await buf1.write("Hello2!".toBytes())
           count.dec
 
       var writerFut = writer()
diff --git a/tests/testinterop.nim b/tests/testinterop.nim
index c33d26826..8ce56e06d 100644
--- a/tests/testinterop.nim
+++ b/tests/testinterop.nim
@@ -65,7 +65,7 @@ proc testPubSubDaemonPublish(gossip: bool = false,
                              count: int = 1): Future[bool] {.async.} =
   var pubsubData = "TEST MESSAGE"
   var testTopic = "test-topic"
-  var msgData = cast[seq[byte]](pubsubData)
+  var msgData = pubsubData.toBytes()
 
   var flags = {PSFloodSub}
   if gossip:
@@ -80,7 +80,7 @@ proc testPubSubDaemonPublish(gossip: bool = false,
   var finished = false
   var times = 0
   proc nativeHandler(topic: string, data: seq[byte]) {.async.} =
-    let smsg = cast[string](data)
+    let smsg = string.fromBytes(data)
     check smsg == pubsubData
     times.inc()
     if times >= count and not finished:
@@ -116,7 +116,7 @@ proc testPubSubNodePublish(gossip: bool = false,
                            count: int = 1): Future[bool] {.async.} =
   var pubsubData = "TEST MESSAGE"
   var testTopic = "test-topic"
-  var msgData = cast[seq[byte]](pubsubData)
+  var msgData = pubsubData.toBytes()
 
   var flags = {PSFloodSub}
   if gossip:
@@ -139,7 +139,7 @@ proc testPubSubNodePublish(gossip: bool = false,
   proc pubsubHandler(api: DaemonAPI,
                      ticket: PubsubTicket,
                      message: PubSubMessage): Future[bool] {.async.} =
-    let smsg = cast[string](message.data)
+    let smsg = string.fromBytes(message.data)
     check smsg == pubsubData
     times.inc()
     if times >= count and not finished:
@@ -184,11 +184,11 @@ suite "Interop":
 
       var testFuture = newFuture[void]("test.future")
       proc daemonHandler(api: DaemonAPI, stream: P2PStream) {.async.} =
-        check cast[string](await stream.transp.readLp()) == "test 1"
+        check string.fromBytes(await stream.transp.readLp()) == "test 1"
         asyncDiscard stream.transp.writeLp("test 2")
 
         await sleepAsync(10.millis)
-        check cast[string](await stream.transp.readLp()) == "test 3"
+        check string.fromBytes(await stream.transp.readLp()) == "test 3"
         asyncDiscard stream.transp.writeLp("test 4")
         testFuture.complete()
 
@@ -197,11 +197,11 @@ suite "Interop":
                                                            daemonPeer.addresses),
                                                            protos[0])
       await conn.writeLp("test 1")
-      check "test 2" == cast[string]((await conn.readLp(1024)))
+      check "test 2" == string.fromBytes((await conn.readLp(1024)))
       await sleepAsync(10.millis)
 
       await conn.writeLp("test 3")
-      check "test 4" == cast[string]((await conn.readLp(1024)))
+      check "test 4" == string.fromBytes((await conn.readLp(1024)))
 
       await wait(testFuture, 10.secs)
       await conn.close()
@@ -265,7 +265,7 @@ suite "Interop":
 
       var testFuture = newFuture[string]("test.future")
       proc nativeHandler(conn: Connection, proto: string) {.async.} =
-        var line = cast[string](await conn.readLp(1024))
+        var line = string.fromBytes(await conn.readLp(1024))
         check line == test
         testFuture.complete(line)
         await conn.close()
@@ -300,11 +300,11 @@ suite "Interop":
 
       var testFuture = newFuture[void]("test.future")
       proc nativeHandler(conn: Connection, proto: string) {.async.} =
-        check "test 1" == cast[string](await conn.readLp(1024))
-        await conn.writeLp(cast[seq[byte]]("test 2"))
+        check "test 1" == string.fromBytes(await conn.readLp(1024))
+        await conn.writeLp("test 2".toBytes())
 
-        check "test 3" == cast[string](await conn.readLp(1024))
-        await conn.writeLp(cast[seq[byte]]("test 4"))
+        check "test 3" == string.fromBytes(await conn.readLp(1024))
+        await conn.writeLp("test 4".toBytes())
 
         testFuture.complete()
         await conn.close()
@@ -325,10 +325,10 @@ suite "Interop":
       var stream = await daemonNode.openStream(nativePeer.peerId, protos)
 
       asyncDiscard stream.transp.writeLp("test 1")
-      check "test 2" == cast[string](await stream.transp.readLp())
+      check "test 2" == string.fromBytes(await stream.transp.readLp())
 
       asyncDiscard stream.transp.writeLp("test 3")
-      check "test 4" == cast[string](await stream.transp.readLp())
+      check "test 4" == string.fromBytes(await stream.transp.readLp())
 
       await wait(testFuture, 10.secs)
 
@@ -349,9 +349,9 @@ suite "Interop":
       var testFuture = newFuture[int]("test.future")
       proc nativeHandler(conn: Connection, proto: string) {.async.} =
         while count < 10:
-          var line = cast[string](await conn.readLp(1024))
+          var line = string.fromBytes(await conn.readLp(1024))
           check line == test
-          await conn.writeLp(cast[seq[byte]](test))
+          await conn.writeLp(test.toBytes())
           count.inc()
 
         testFuture.complete(count)
@@ -376,7 +376,7 @@ suite "Interop":
       while count2 < 10:
         discard await stream.transp.writeLp(test)
         let line = await stream.transp.readLp()
-        check test == cast[string](line)
+        check test == string.fromBytes(line)
         inc(count2)
 
       result = 10 == (await wait(testFuture, 1.minutes))
diff --git a/tests/testmultistream.nim b/tests/testmultistream.nim
index ecb64f58c..217225877 100644
--- a/tests/testmultistream.nim
+++ b/tests/testmultistream.nim
@@ -192,7 +192,7 @@ suite "Multistream select":
       let conn = newConnection(newTestLsStream(testLsHandler))
       let done = newFuture[void]()
       proc testLsHandler(proto: seq[byte]) {.async, gcsafe.} =
-        var strProto: string = cast[string](proto)
+        var strProto: string = string.fromBytes(proto)
         check strProto == "\x26/test/proto1/1.0.0\n/test/proto2/1.0.0\n"
         await conn.close()
         done.complete()
@@ -270,7 +270,7 @@ suite "Multistream select":
 
       check (await msDial.select(conn, "/test/proto/1.0.0")) == true
 
-      let hello = cast[string](await conn.readLp(1024))
+      let hello = string.fromBytes(await conn.readLp(1024))
       result = hello == "Hello!"
       await conn.close()
 
@@ -366,7 +366,7 @@ suite "Multistream select":
       check (await msDial.select(conn,
         @["/test/proto/1.0.0", "/test/no/proto/1.0.0"])) == "/test/proto/1.0.0"
 
-      let hello = cast[string](await conn.readLp(1024))
+      let hello = string.fromBytes(await conn.readLp(1024))
       result = hello == "Hello!"
 
       await conn.close()
@@ -405,7 +405,7 @@ suite "Multistream select":
 
       check (await msDial.select(conn, @["/test/proto2/1.0.0", "/test/proto1/1.0.0"])) == "/test/proto2/1.0.0"
 
-      result = cast[string](await conn.readLp(1024)) == "Hello from /test/proto2/1.0.0!"
+      result = string.fromBytes(await conn.readLp(1024)) == "Hello from /test/proto2/1.0.0!"
 
       await conn.close()
       await transport2.close()
diff --git a/tests/testnoise.nim b/tests/testnoise.nim
index 778328564..c77ac86cf 100644
--- a/tests/testnoise.nim
+++ b/tests/testnoise.nim
@@ -10,7 +10,7 @@
 {.used.}
 
 import unittest, tables
-import chronos
+import chronos, stew/byteutils
 import chronicles
 import nimcrypto/sysrand
 import ../libp2p/crypto/crypto
@@ -41,7 +41,7 @@ type
 
 method init(p: TestProto) {.gcsafe.} =
   proc handle(conn: Connection, proto: string) {.async, gcsafe.} =
-    let msg = cast[string](await conn.readLp(1024))
+    let msg = string.fromBytes(await conn.readLp(1024))
     check "Hello!" == msg
     await conn.writeLp("Hello!")
     await conn.close()
@@ -107,7 +107,7 @@ suite "Noise":
       await transport1.close()
       await transport2.close()
 
-      result = cast[string](msg) == "Hello!"
+      result = string.fromBytes(msg) == "Hello!"
 
     check:
       waitFor(testListenerDialer()) == true
@@ -127,7 +127,7 @@ suite "Noise":
           await conn.close()
         var msg = newSeq[byte](6)
         await sconn.readExactly(addr msg[0], 6)
-        check cast[string](msg) == "Hello!"
+        check string.fromBytes(msg) == "Hello!"
         readTask.complete()
 
       let
@@ -218,7 +218,7 @@ suite "Noise":
       awaiters.add(await switch2.start())
       let conn = await switch2.dial(switch1.peerInfo, TestCodec)
       await conn.writeLp("Hello!")
-      let msg = cast[string](await conn.readLp(1024))
+      let msg = string.fromBytes(await conn.readLp(1024))
       check "Hello!" == msg
       await conn.close()
 
diff --git a/tests/testtransport.nim b/tests/testtransport.nim
index d7c3fc74b..d943c10ac 100644
--- a/tests/testtransport.nim
+++ b/tests/testtransport.nim
@@ -1,7 +1,7 @@
 {.used.}
 
 import unittest
-import chronos
+import chronos, stew/byteutils
 import ../libp2p/[connection,
                   transports/transport,
                   transports/tcptransport,
@@ -35,7 +35,7 @@ suite "TCP transport":
       await streamTransport.closeWait()
       await transport.close()
 
-      result = cast[string](msg) == "Hello!"
+      result = string.fromBytes(msg) == "Hello!"
 
     check:
       waitFor(testListener()) == true
@@ -47,7 +47,7 @@ suite "TCP transport":
       proc connHandler(conn: Connection) {.async, gcsafe.} =
         var msg = newSeq[byte](6)
         await conn.readExactly(addr msg[0], 6)
-        check cast[string](msg) == "Hello!"
+        check string.fromBytes(msg) == "Hello!"
         await conn.close()
         handlerWait.complete()
 
@@ -87,7 +87,7 @@ suite "TCP transport":
       let conn = await transport.dial(ma)
       var msg = newSeq[byte](6)
       await conn.readExactly(addr msg[0], 6)
-      result = cast[string](msg) == "Hello!"
+      result = string.fromBytes(msg) == "Hello!"
 
       await handlerWait.wait(5000.millis) # when no issues will not wait that long!
 
@@ -108,7 +108,7 @@ suite "TCP transport":
                         transp: StreamTransport) {.async, gcsafe.} =
         var rstream = newAsyncStreamReader(transp)
         let msg = await rstream.read(6)
-        check cast[string](msg) == "Hello!"
+        check string.fromBytes(msg) == "Hello!"
 
         await rstream.closeWait()
         await transp.closeWait()
@@ -159,7 +159,7 @@ suite "TCP transport":
       await transport2.close()
       await transport1.close()
 
-      result = cast[string](msg) == "Hello!"
+      result = string.fromBytes(msg) == "Hello!"
 
     check:
       waitFor(testListenerDialer()) == true
@@ -171,7 +171,7 @@ suite "TCP transport":
       proc connHandler(conn: Connection) {.async, gcsafe.} =
         var msg = newSeq[byte](6)
         await conn.readExactly(addr msg[0], 6)
-        check cast[string](msg) == "Hello!"
+        check string.fromBytes(msg) == "Hello!"
         await conn.close()
         handlerWait.complete()