diff --git a/fs2-aws-s3/src/main/scala/fs2/aws/s3/S3.scala b/fs2-aws-s3/src/main/scala/fs2/aws/s3/S3.scala
index 5af07eba..0af599f0 100644
--- a/fs2-aws-s3/src/main/scala/fs2/aws/s3/S3.scala
+++ b/fs2-aws-s3/src/main/scala/fs2/aws/s3/S3.scala
@@ -1,7 +1,7 @@
 package fs2.aws.s3
 
-import cats.effect.*
-import cats.implicits.*
+import cats.effect.Concurrent
+import cats.syntax.all.*
 import cats.{Applicative, ApplicativeThrow, ~>}
 import eu.timepit.refined.auto.*
 import fs2.aws.s3.S3.MultipartETagValidation
@@ -13,8 +13,6 @@ import software.amazon.awssdk.core.async.{AsyncRequestBody, AsyncResponseTransfo
 import software.amazon.awssdk.services.s3.model.*
 
 import java.security.MessageDigest
-import scala.collection.immutable.ArraySeq
-import scala.collection.immutable.ArraySeq.unsafeWrapArray
 import scala.jdk.CollectionConverters.*
 import scala.util.control.NoStackTrace
 
@@ -94,7 +92,7 @@ object S3 {
   }
 
   /** It creates an instance of the purely functional S3 API. */
-  def create[F[_]: Async](s3: S3AsyncClientOp[F]): S3[F] =
+  def create[F[_]: Concurrent](s3: S3AsyncClientOp[F]): S3[F] =
     new S3[F] {
 
       /** Deletes a file in a single request.
@@ -194,12 +192,10 @@ object S3 {
         ): Pipe[F, List[PartProcessingOutcome], (Option[ETag], Option[Checksum], Option[PartId])] =
           _.evalMap[F, (Option[ETag], Option[Checksum], Option[PartId])] {
             case Nil =>
-              cancelUpload(uploadId) *>
-                Async[F]
-                  .ifM(Async[F].pure(uploadEmptyFiles))(
-                    uploadEmptyFile.map(eTag => (Option(eTag.eTag()), Option.empty[Checksum], Option.empty[PartId])),
-                    Async[F].pure((Option.empty[ETag], Option.empty[Checksum], Option.empty[PartId]))
-                  )
+              cancelUpload(uploadId) *> (
+                if (uploadEmptyFiles) uploadEmptyFile.map(eTag => Option(eTag.eTag))
+                else Applicative[F].pure(Option.empty[ETag])
+              ).map((_, Option.empty[Checksum], Option.empty[PartId]))
             case tags =>
               val parts = tags.map { case PartProcessingOutcome(t, i, _) =>
                 CompletedPart.builder().partNumber(i).eTag(t).build()
@@ -272,7 +268,7 @@ object S3 {
               .through(uploadPart(uploadId))
               .fold[List[PartProcessingOutcome]](List.empty)(_ :+ _)
               .through(completeUpload(uploadId))
-              .handleErrorWith(ex => fs2.Stream.eval(cancelUpload(uploadId) >> Sync[F].raiseError(ex)))
+              .handleErrorWith(ex => fs2.Stream.eval(cancelUpload(uploadId) >> ApplicativeThrow[F].raiseError(ex)))
             _ <- fs2.Stream.eval(validateETag(eTag, maxPartNum, checksum))
           } yield eTag
 
@@ -294,7 +290,7 @@ object S3 {
               AsyncResponseTransformer.toBytes[GetObjectResponse]
             )
           )
-          .flatMap(r => fs2.Stream.chunk(Chunk(ArraySeq.unsafeWrapArray(r.asByteArray)*)))
+          .flatMap(r => fs2.Stream.chunk(Chunk.array(r.asByteArrayUnsafe)))
 
       /** Reads a file in multiple parts of the specified @partSize per request. Suitable for big files.
         *
@@ -328,23 +324,11 @@ object S3 {
             .last
             .flatMap {
               case Some(resp) =>
-                Pull.eval {
-                  Async[F].blocking {
-                    val bs  = resp.asByteArray()
-                    val len = bs.length
-                    if (len < 0) None else Some(Chunk(unsafeWrapArray(bs)*))
-                  }
-                }
+                val chunk = Chunk.array(resp.asByteArrayUnsafe)
+                Pull.output(chunk) >> (if (chunk.size < chunkSizeBytes) Pull.done else go(offset + chunk.size))
               case None =>
-                Pull.eval(none.pure[F])
-            }
-            .flatMap {
-              case Some(o) =>
-                if (o.size < chunkSizeBytes) Pull.output(o)
-                else Pull.output(o) >> go(offset + o.size)
-              case None => Pull.done
+                Pull.done
             }
-
         go(0).stream
       }