diff --git a/chronos/internal/asyncengine.nim b/chronos/internal/asyncengine.nim
index d4e803c..578bfdf 100644
--- a/chronos/internal/asyncengine.nim
+++ b/chronos/internal/asyncengine.nim
@@ -1125,14 +1125,18 @@ proc addTimer*(at: uint64, cb: CallbackFunc, udata: pointer = nil) {.
 proc removeTimer*(at: Moment, cb: CallbackFunc, udata: pointer = nil) =
   ## Remove timer callback ``cb`` with absolute timestamp ``at`` from waiting
   ## queue.
-  let loop = getThreadDispatcher()
-  var list = cast[seq[TimerCallback]](loop.timers)
-  var index = -1
-  for i in 0..<len(list):
-    if list[i].finishAt == at and list[i].function.function == cb and
-       list[i].function.udata == udata:
-      index = i
-      break
+  let
+    loop = getThreadDispatcher()
+    index =
+      block:
+        var res = -1
+        for i in 0 ..< len(loop.timers):
+          if (loop.timers[i].finishAt == at) and
+             (loop.timers[i].function.function == cb) and
+             (loop.timers[i].function.udata == udata):
+            res = i
+            break
+        res
   if index != -1:
     loop.timers.del(index)
 
diff --git a/tests/testasyncstream.nim b/tests/testasyncstream.nim
index c5701bb..86b7357 100644
--- a/tests/testasyncstream.nim
+++ b/tests/testasyncstream.nim
@@ -7,6 +7,7 @@
 #              MIT license (LICENSE-MIT)
 import unittest2
 import bearssl/[x509]
+import stew/byteutils
 import ".."/chronos/unittest2/asynctests
 import ".."/chronos/streams/[tlsstream, chunkstream, boundstream]
 
@@ -102,11 +103,11 @@ suite "AsyncStream test suite":
       var transp = await connect(server.localAddress())
       var rstream = newAsyncStreamReader(transp)
       await rstream.readExactly(addr buffer[0], 10)
-      check cast[string](buffer) == "0000000000"
+      check string.fromBytes(buffer) == "0000000000"
       await rstream.readExactly(addr buffer[0], 10)
-      check cast[string](buffer) == "1111111111"
+      check string.fromBytes(buffer) == "1111111111"
       await rstream.readExactly(addr buffer[0], 10)
-      check cast[string](buffer) == "2222222222"
+      check string.fromBytes(buffer) == "2222222222"
       await rstream.closeWait()
       await transp.closeWait()
       await server.join()
@@ -135,15 +136,15 @@ suite "AsyncStream test suite":
       var r1 = await rstream.readUntil(addr buffer[0], len(buffer), sep)
       check:
         r1 == 13
-        cast[string](buffer) == "0000000000NNz"
+        string.fromBytes(buffer) == "0000000000NNz"
       var r2 = await rstream.readUntil(addr buffer[0], len(buffer), sep)
       check:
         r2 == 13
-        cast[string](buffer) == "1111111111NNz"
+        string.fromBytes(buffer) == "1111111111NNz"
       var r3 = await rstream.readUntil(addr buffer[0], len(buffer), sep)
       check:
         r3 == 13
-        cast[string](buffer) == "2222222222NNz"
+        string.fromBytes(buffer) == "2222222222NNz"
 
       await rstream.closeWait()
       await transp.closeWait()
@@ -198,9 +199,9 @@ suite "AsyncStream test suite":
       var transp = await connect(server.localAddress())
       var rstream = newAsyncStreamReader(transp)
       var buf1 = await rstream.read(10)
-      check cast[string](buf1) == "0000000000"
+      check string.fromBytes(buf1) == "0000000000"
       var buf2 = await rstream.read()
-      check cast[string](buf2) == "11111111112222222222"
+      check string.fromBytes(buf2) == "11111111112222222222"
       await rstream.closeWait()
       await transp.closeWait()
       await server.join()
@@ -228,12 +229,12 @@ suite "AsyncStream test suite":
       check:
         res1 == 10
       var buf1 = await rstream.read(10)
-      check cast[string](buf1) == "1111111111"
+      check string.fromBytes(buf1) == "1111111111"
       var res2 = await rstream.consume(10)
       check:
         res2 == 10
       var buf2 = await rstream.read(10)
-      check cast[string](buf2) == "3333333333"
+      check string.fromBytes(buf2) == "3333333333"
       await rstream.closeWait()
       await transp.closeWait()
       await server.join()
@@ -255,7 +256,7 @@ suite "AsyncStream test suite":
         await wstream2.write("00000")
         await wstream2.write(addr s1[0], len(s1))
         await wstream2.write("11111")
-        await wstream2.write(cast[seq[byte]](s2))
+        await wstream2.write(s2.toBytes())
         await wstream2.write("22222")
         await wstream2.write(addr s3[0], len(s3))
 
@@ -275,11 +276,11 @@ suite "AsyncStream test suite":
       var rstream = newAsyncStreamReader(transp)
       var rstream2 = newChunkedStreamReader(rstream)
       await rstream2.readExactly(addr buffer[0], 10)
-      check cast[string](buffer) == "0000000000"
+      check string.fromBytes(buffer) == "0000000000"
       await rstream2.readExactly(addr buffer[0], 10)
-      check cast[string](buffer) == "1111111111"
+      check string.fromBytes(buffer) == "1111111111"
       await rstream2.readExactly(addr buffer[0], 10)
-      check cast[string](buffer) == "2222222222"
+      check string.fromBytes(buffer) == "2222222222"
 
       # We need to consume all the stream with finish markers, but there will
       # be no actual data.
@@ -309,7 +310,7 @@ suite "AsyncStream test suite":
         await wstream2.write("11111")
         await wstream2.write(s2)
         await wstream2.write("22222")
-        await wstream2.write(cast[seq[byte]](s3))
+        await wstream2.write(s3.toBytes())
         await wstream2.finish()
         await wstream.finish()
         await wstream2.closeWait()
@@ -330,15 +331,15 @@ suite "AsyncStream test suite":
       var r1 = await rstream2.readUntil(addr buffer[0], len(buffer), sep)
       check:
         r1 == 13
-        cast[string](buffer) == "0000000000NNz"
+        string.fromBytes(buffer) == "0000000000NNz"
       var r2 = await rstream2.readUntil(addr buffer[0], len(buffer), sep)
       check:
         r2 == 13
-        cast[string](buffer) == "1111111111NNz"
+        string.fromBytes(buffer) == "1111111111NNz"
       var r3 = await rstream2.readUntil(addr buffer[0], len(buffer), sep)
       check:
         r3 == 13
-        cast[string](buffer) == "2222222222NNz"
+        string.fromBytes(buffer) == "2222222222NNz"
 
       # We need to consume all the stream with finish markers, but there will
       # be no actual data.
@@ -411,7 +412,7 @@ suite "AsyncStream test suite":
         var s3 = "2222222222"
         await wstream2.write("0000000000")
         await wstream2.write(s2)
-        await wstream2.write(cast[seq[byte]](s3))
+        await wstream2.write(s3.toBytes())
         await wstream2.finish()
         await wstream.finish()
         await wstream2.closeWait()
@@ -427,9 +428,9 @@ suite "AsyncStream test suite":
       var rstream = newAsyncStreamReader(transp)
       var rstream2 = newChunkedStreamReader(rstream)
       var buf1 = await rstream2.read(10)
-      check cast[string](buf1) == "0000000000"
+      check string.fromBytes(buf1) == "0000000000"
       var buf2 = await rstream2.read()
-      check cast[string](buf2) == "11111111112222222222"
+      check string.fromBytes(buf2) == "11111111112222222222"
 
       # read() call will consume all the bytes and finish markers too, so
       # we just check stream for EOF.
@@ -452,7 +453,7 @@ suite "AsyncStream test suite":
         var wstream2 = newChunkedStreamWriter(wstream)
 
         var s1 = "00000"
-        var s2 = cast[seq[byte]]("11111")
+        var s2 = "11111".toBytes()
         var s3 = "22222"
 
         await wstream2.write("00000")
@@ -482,12 +483,12 @@ suite "AsyncStream test suite":
       check:
         res1 == 10
       var buf1 = await rstream2.read(10)
-      check cast[string](buf1) == "1111111111"
+      check string.fromBytes(buf1) == "1111111111"
       var res2 = await rstream2.consume(10)
       check:
         res2 == 10
       var buf2 = await rstream2.read(10)
-      check cast[string](buf2) == "3333333333"
+      check string.fromBytes(buf2) == "3333333333"
 
       # We need to consume all the stream with finish markers, but there will
       # be no actual data.
@@ -596,7 +597,7 @@ suite "ChunkedStream test suite":
       var rstream = newAsyncStreamReader(transp)
       var rstream2 = newChunkedStreamReader(rstream)
       var res = await rstream2.read()
-      var ress = cast[string](res)
+      var ress = string.fromBytes(res)
       await rstream2.closeWait()
       await rstream.closeWait()
       await transp.closeWait()
@@ -917,7 +918,7 @@ suite "TLSStream test suite":
     await cwriter.closeWait()
     await conn.closeWait()
     await server.join()
-    return cast[string](res) == (testMessage & "\r\n")
+    return string.fromBytes(res) == (testMessage & "\r\n")
 
   test "Simple server with RSA self-signed certificate":
     let res = waitFor(checkSSLServer(SelfSignedRsaKey, SelfSignedRsaCert))
@@ -961,7 +962,7 @@ suite "TLSStream test suite":
       await cwriter.closeWait()
       await conn.closeWait()
       await server.join()
-      return cast[string](res)
+      return string.fromBytes(res)
     let res = waitFor checkTrustAnchors("Some message")
     check res == "Some message\r\n"
 
diff --git a/tests/testdatagram.nim b/tests/testdatagram.nim
index ae7ab23..c941761 100644
--- a/tests/testdatagram.nim
+++ b/tests/testdatagram.nim
@@ -6,6 +6,7 @@
 #  Apache License, version 2.0, (LICENSE-APACHEv2)
 #              MIT license (LICENSE-MIT)
 import std/[strutils, net]
+import stew/byteutils
 import ".."/chronos/unittest2/asynctests
 import ".."/chronos
 
@@ -474,7 +475,7 @@ suite "Datagram Transport test suite":
     proc clientMark(transp: DatagramTransport,
                      raddr: TransportAddress): Future[void] {.async.} =
       var bmsg = transp.getMessage()
-      var smsg = cast[string](bmsg)
+      var smsg = string.fromBytes(bmsg)
       if smsg == expectMessage:
         inc(res)
       transp.close()
@@ -486,7 +487,7 @@ suite "Datagram Transport test suite":
 
   proc testAnyAddress(): Future[int] {.async.} =
     var expectStr = "ANYADDRESS MESSAGE"
-    var expectSeq = cast[seq[byte]](expectStr)
+    var expectSeq = expectStr.toBytes()
     let ta = initTAddress("0.0.0.0:0")
     var res = 0
     var event = newAsyncEvent()
@@ -494,7 +495,7 @@ suite "Datagram Transport test suite":
     proc clientMark1(transp: DatagramTransport,
                      raddr: TransportAddress): Future[void] {.async.} =
       var bmsg = transp.getMessage()
-      var smsg = cast[string](bmsg)
+      var smsg = string.fromBytes(bmsg)
       if smsg == expectStr:
         inc(res)
       event.fire()
@@ -545,7 +546,7 @@ suite "Datagram Transport test suite":
     proc process1(transp: DatagramTransport,
                   raddr: TransportAddress): Future[void] {.async.} =
       var bmsg = transp.getMessage()
-      var smsg = cast[string](bmsg)
+      var smsg = string.fromBytes(bmsg)
       if smsg == expectStr:
         inc(res)
       event.fire()
diff --git a/tests/testhttpclient.nim b/tests/testhttpclient.nim
index f08b3c5..1d9992f 100644
--- a/tests/testhttpclient.nim
+++ b/tests/testhttpclient.nim
@@ -9,7 +9,7 @@ import std/[strutils, sha1]
 import ".."/chronos/unittest2/asynctests
 import ".."/chronos,
        ".."/chronos/apps/http/[httpserver, shttpserver, httpclient]
-import stew/base10
+import stew/[byteutils, base10]
 
 {.used.}
 
@@ -157,7 +157,7 @@ suite "HTTP client testing suite":
       var req = HttpClientRequestRef.new(session, ha, item[0])
       let response = await fetch(req)
       if response.status == 200:
-        let data = cast[string](response.data)
+        let data = string.fromBytes(response.data)
         if data == item[1]:
           inc(counter)
       await req.closeWait()
@@ -173,7 +173,7 @@ suite "HTTP client testing suite":
       var req = HttpClientRequestRef.new(session, ha, item[0])
       let response = await fetch(req)
       if response.status == 200:
-        let data = cast[string](response.data)
+        let data = string.fromBytes(response.data)
         if data == item[1]:
           inc(counter)
       await req.closeWait()
@@ -318,7 +318,7 @@ suite "HTTP client testing suite":
         of "/test/big_request":
           if request.hasBody():
             let body = await request.getBody()
-            let digest = $secureHash(cast[string](body))
+            let digest = $secureHash(string.fromBytes(body))
             return await request.respond(Http200, digest)
           else:
             return await request.respond(Http400, "Missing content body")
@@ -348,7 +348,7 @@ suite "HTTP client testing suite":
         session, ha, item[0], headers = headers
       )
 
-      var expectDigest = $secureHash(cast[string](data))
+      var expectDigest = $secureHash(string.fromBytes(data))
       # Sending big request by 1024bytes long chunks
       var writer = await open(request)
       var offset = 0
@@ -364,7 +364,7 @@ suite "HTTP client testing suite":
 
       if response.status == 200:
         var res = await response.getBodyBytes()
-        if cast[string](res) == expectDigest:
+        if string.fromBytes(res) == expectDigest:
           inc(counter)
       await response.closeWait()
       await request.closeWait()
@@ -388,7 +388,7 @@ suite "HTTP client testing suite":
         of "/test/big_chunk_request":
           if request.hasBody():
             let body = await request.getBody()
-            let digest = $secureHash(cast[string](body))
+            let digest = $secureHash(string.fromBytes(body))
             return await request.respond(Http200, digest)
           else:
             return await request.respond(Http400, "Missing content body")
@@ -418,7 +418,7 @@ suite "HTTP client testing suite":
         session, ha, item[0], headers = headers
       )
 
-      var expectDigest = $secureHash(cast[string](data))
+      var expectDigest = $secureHash(string.fromBytes(data))
       # Sending big request by 1024bytes long chunks
       var writer = await open(request)
       var offset = 0
@@ -434,7 +434,7 @@ suite "HTTP client testing suite":
 
       if response.status == 200:
         var res = await response.getBodyBytes()
-        if cast[string](res) == expectDigest:
+        if string.fromBytes(res) == expectDigest:
           inc(counter)
       await response.closeWait()
       await request.closeWait()
@@ -491,12 +491,12 @@ suite "HTTP client testing suite":
       ]
       var request = HttpClientRequestRef.new(
         session, ha, MethodPost, headers = headers,
-        body = cast[seq[byte]](PostRequests[0][1]))
+        body = PostRequests[0][1].toBytes())
       var response = await send(request)
 
       if response.status == 200:
         var res = await response.getBodyBytes()
-        if cast[string](res) == PostRequests[0][2]:
+        if string.fromBytes(res) == PostRequests[0][2]:
           inc(counter)
       await response.closeWait()
       await request.closeWait()
@@ -532,7 +532,7 @@ suite "HTTP client testing suite":
       var response = await request.finish()
       if response.status == 200:
         var res = await response.getBodyBytes()
-        if cast[string](res) == PostRequests[1][2]:
+        if string.fromBytes(res) == PostRequests[1][2]:
           inc(counter)
       await response.closeWait()
       await request.closeWait()
@@ -601,7 +601,7 @@ suite "HTTP client testing suite":
       var response = await send(request)
       if response.status == 200:
         var res = await response.getBodyBytes()
-        if cast[string](res) == PostRequests[0][3]:
+        if string.fromBytes(res) == PostRequests[0][3]:
           inc(counter)
       await response.closeWait()
       await request.closeWait()
@@ -634,7 +634,7 @@ suite "HTTP client testing suite":
       let response = await request.finish()
       if response.status == 200:
         var res = await response.getBodyBytes()
-        if cast[string](res) == PostRequests[1][3]:
+        if string.fromBytes(res) == PostRequests[1][3]:
           inc(counter)
       await response.closeWait()
       await request.closeWait()