diff --git a/cache/src/main/scala/coursier/Cache.scala b/cache/src/main/scala/coursier/Cache.scala
index 9949e9e12..ae56f0cf6 100644
--- a/cache/src/main/scala/coursier/Cache.scala
+++ b/cache/src/main/scala/coursier/Cache.scala
@@ -1127,20 +1127,6 @@ object Cache {
 
   var bufferSize = 1024*1024
 
-  def readFullySync(is: InputStream) = {
-    val buffer = new ByteArrayOutputStream()
-    val data = Array.ofDim[Byte](16384)
-
-    var nRead = is.read(data, 0, data.length)
-    while (nRead != -1) {
-      buffer.write(data, 0, nRead)
-      nRead = is.read(data, 0, data.length)
-    }
-
-    buffer.flush()
-    buffer.toByteArray
-  }
-
   def withContent(is: InputStream, f: (Array[Byte], Int) => Unit): Unit = {
     val data = Array.ofDim[Byte](16384)
 
diff --git a/cache/src/main/scala/coursier/internal/FileUtil.scala b/cache/src/main/scala/coursier/internal/FileUtil.scala
index 5b8bcc876..5a6970101 100644
--- a/cache/src/main/scala/coursier/internal/FileUtil.scala
+++ b/cache/src/main/scala/coursier/internal/FileUtil.scala
@@ -66,7 +66,7 @@ object FileUtil {
     }
   }
 
-  private def readFully(is: InputStream): Array[Byte] = {
+  def readFully(is: InputStream): Array[Byte] = {
     val buffer = new ByteArrayOutputStream
     val data = Array.ofDim[Byte](16384)
 
diff --git a/cli/src/main/scala-2.12/coursier/cli/Bootstrap.scala b/cli/src/main/scala-2.12/coursier/cli/Bootstrap.scala
index 84ee3311c..5b1b7dac7 100644
--- a/cli/src/main/scala-2.12/coursier/cli/Bootstrap.scala
+++ b/cli/src/main/scala-2.12/coursier/cli/Bootstrap.scala
@@ -82,7 +82,7 @@ object Bootstrap extends CaseApp[BootstrapOptions] {
 
       val bootstrapJar =
         Option(Thread.currentThread().getContextClassLoader.getResourceAsStream("bootstrap.jar")) match {
-          case Some(is) => Cache.readFullySync(is)
+          case Some(is) => FileUtil.readFully(is)
           case None =>
             Console.err.println(s"Error: bootstrap JAR not found")
             sys.exit(1)
@@ -165,7 +165,7 @@ object Bootstrap extends CaseApp[BootstrapOptions] {
         entry.setTime(f.lastModified())
 
         outputZip.putNextEntry(entry)
-        outputZip.write(Cache.readFullySync(new FileInputStream(f)))
+        outputZip.write(FileUtil.readFully(new FileInputStream(f)))
         outputZip.closeEntry()
       }
 
diff --git a/cli/src/main/scala-2.12/coursier/cli/scaladex/Scaladex.scala b/cli/src/main/scala-2.12/coursier/cli/scaladex/Scaladex.scala
index 1fa1030fe..a96a1dfd8 100644
--- a/cli/src/main/scala-2.12/coursier/cli/scaladex/Scaladex.scala
+++ b/cli/src/main/scala-2.12/coursier/cli/scaladex/Scaladex.scala
@@ -40,7 +40,7 @@ object Scaladex {
 
         val b = try {
           conn = new java.net.URL(url).openConnection().asInstanceOf[HttpURLConnection]
-          coursier.Platform.readFullySync(conn.getInputStream)
+          coursier.internal.FileUtil.readFully(conn.getInputStream)
         } finally {
           if (conn != null)
             coursier.Cache.closeConn(conn)
diff --git a/cli/src/main/scala-2.12/coursier/cli/util/Zip.scala b/cli/src/main/scala-2.12/coursier/cli/util/Zip.scala
index 23ed3263b..67c5d1494 100644
--- a/cli/src/main/scala-2.12/coursier/cli/util/Zip.scala
+++ b/cli/src/main/scala-2.12/coursier/cli/util/Zip.scala
@@ -2,8 +2,6 @@ package coursier.cli.util
 
 import java.util.zip.{ZipEntry, ZipInputStream}
 
-import coursier.Platform
-
 object Zip {
 
   def zipEntries(zipStream: ZipInputStream): Iterator[(ZipEntry, Array[Byte])] =
@@ -17,7 +15,7 @@ object Zip {
       def hasNext = nextEntry.nonEmpty
       def next() = {
         val ent = nextEntry.get
-        val data = Platform.readFullySync(zipStream)
+        val data = coursier.internal.FileUtil.readFully(zipStream)
 
         update()
 
diff --git a/cli/src/test/scala-2.12/coursier/cli/CliBootstrapIntegrationTest.scala b/cli/src/test/scala-2.12/coursier/cli/CliBootstrapIntegrationTest.scala
index 6ed82df8c..8f6dce705 100644
--- a/cli/src/test/scala-2.12/coursier/cli/CliBootstrapIntegrationTest.scala
+++ b/cli/src/test/scala-2.12/coursier/cli/CliBootstrapIntegrationTest.scala
@@ -22,7 +22,7 @@ class CliBootstrapIntegrationTest extends FlatSpec with CliTestLib {
       if (e == null)
         throw new NoSuchElementException(s"Entry $path in zip file")
       else if (e.getName == path)
-        coursier.Platform.readFullySync(zis)
+        coursier.internal.FileUtil.readFully(zis)
       else
         zipEntryContent(zis, path)
     }
@@ -53,7 +53,7 @@ class CliBootstrapIntegrationTest extends FlatSpec with CliTestLib {
 
       val content = try {
         fis = new FileInputStream(bootstrapFile)
-        coursier.Platform.readFullySync(fis)
+        coursier.internal.FileUtil.readFully(fis)
       } finally {
         if (fis != null) fis.close()
       }
diff --git a/cache/src/main/scala/coursier/Platform.scala b/tests/jvm/src/test/scala/coursier/Platform.scala
similarity index 100%
rename from cache/src/main/scala/coursier/Platform.scala
rename to tests/jvm/src/test/scala/coursier/Platform.scala