diff --git a/filesystems/blob/src/main/scala/cromwell/filesystems/blob/BlobFileSystemManager.scala b/filesystems/blob/src/main/scala/cromwell/filesystems/blob/BlobFileSystemManager.scala
index 7a9f0a68a9f..1798a19df1d 100644
--- a/filesystems/blob/src/main/scala/cromwell/filesystems/blob/BlobFileSystemManager.scala
+++ b/filesystems/blob/src/main/scala/cromwell/filesystems/blob/BlobFileSystemManager.scala
@@ -21,7 +21,7 @@ import scala.util.{Failure, Success, Try}
 // We encapsulate this functionality here so that we can easily mock it out, to allow for testing without
 // actually connecting to Blob storage.
 case class FileSystemAPI(private val provider: FileSystemProvider = new AzureFileSystemProvider()) {
-  def getFileSystem(uri: URI): Try[AzureFileSystem] = Try(provider.getFileSystem(uri).asInstanceOf[AzureFileSystem])
+  def getFileSystem(uri: URI): Try[FileSystem] = Try(provider.getFileSystem(uri).asInstanceOf[AzureFileSystem])
   def newFileSystem(uri: URI, config: Map[String, Object]): FileSystem = provider.newFileSystem(uri, config.asJava)
   def closeFileSystem(uri: URI): Option[Unit] = getFileSystem(uri).toOption.map(_.close)
 }