diff --git a/app/current/src/main/scala/io/scalajs/nodejs/fs/package.scala b/app/current/src/main/scala/io/scalajs/nodejs/fs/package.scala
index 195e1695c..926138101 100644
--- a/app/current/src/main/scala/io/scalajs/nodejs/fs/package.scala
+++ b/app/current/src/main/scala/io/scalajs/nodejs/fs/package.scala
@@ -108,15 +108,27 @@ package object fs {
       promiseWithError0[FileIOError](instance.mkdir(path, options, _))
     }
 
+    @inline
+    def mkdtempFuture(prefix: String, options: FileEncodingOptions = ???): Future[String] = {
+      promiseWithError1[FileIOError, String](instance.mkdtemp(prefix, options, _))
+    }
+
     @inline
     def openFuture(path: Buffer | String, flags: Flags, mode: FileMode): Future[FileDescriptor] = {
       promiseWithError1[FileIOError, FileDescriptor](instance.open(path, flags, mode, _))
     }
+
     @inline
     def openFuture(path: Buffer | String, flags: Flags): Future[FileDescriptor] = {
       promiseWithError1[FileIOError, FileDescriptor](instance.open(path, flags, _))
     }
 
+    @enableIf(io.scalajs.nodejs.internal.CompilerSwitches.gteNodeJs12)
+    @inline
+    def openFuture(path: Buffer | String): Future[FileDescriptor] = {
+      promiseWithError1[FileIOError, FileDescriptor](instance.open(path, _))
+    }
+
     @inline
     def readFuture(fd: FileDescriptor,
                    buffer: Buffer,
diff --git a/app/current/src/main/scala/io/scalajs/nodejs/package.scala b/app/current/src/main/scala/io/scalajs/nodejs/package.scala
index 138aed496..f63f2e75d 100644
--- a/app/current/src/main/scala/io/scalajs/nodejs/package.scala
+++ b/app/current/src/main/scala/io/scalajs/nodejs/package.scala
@@ -32,7 +32,7 @@ package object nodejs {
 
   type FileIOError = SystemError
 
-  type FileMode = Int | Null
+  type FileMode = Int
 
   type FileType = Int
 
diff --git a/app/nodejs-v8/src/test/scala/io/scalajs/nodejs/fs/FsAsyncTest.scala b/app/nodejs-v8/src/test/scala/io/scalajs/nodejs/fs/FsAsyncTest.scala
index 4366f920c..72cda86b8 100644
--- a/app/nodejs-v8/src/test/scala/io/scalajs/nodejs/fs/FsAsyncTest.scala
+++ b/app/nodejs-v8/src/test/scala/io/scalajs/nodejs/fs/FsAsyncTest.scala
@@ -4,6 +4,7 @@ import io.scalajs.nodejs.buffer.Buffer
 import org.scalatest.{AsyncFunSpec, BeforeAndAfterEach}
 
 import scala.concurrent.{ExecutionContext, Future}
+import scala.util.{Failure, Success}
 
 class FsAsyncTest extends AsyncFunSpec with BeforeAndAfterEach {
 
@@ -40,5 +41,49 @@ class FsAsyncTest extends AsyncFunSpec with BeforeAndAfterEach {
         }
       }
     }
+
+    describe("accessFuture") {
+      it("should succeed") {
+        for {
+          _ <- Fs.accessFuture("package.json")
+          _ <- Fs.accessFuture("package.json", Fs.constants.R_OK)
+        } yield {
+          succeed
+        }
+      }
+
+      it("should fail: no such file") {
+        Fs.accessFuture("package.json111").transformWith {
+          case Failure(_) => succeed
+          case Success(_) => fail("expected failure")
+        }
+      }
+
+      it("should fail: invalid file mode") {
+        Fs.accessFuture("package.json", Fs.constants.X_OK).transformWith {
+          case Failure(_) => succeed
+          case Success(_) => fail("expected failure")
+        }
+      }
+    }
+
+    describe("appendFileFuture") {
+      it("should support option") {
+        for {
+          _              <- Fs.appendFileFuture("x.AppendFile.txt", "yay")
+          _              <- Fs.appendFileFuture("x.AppendFile.sh", "echo 0", new FileAppendOptions(mode = Fs.constants.X_OK))
+          defaultStat    <- Fs.statFuture("x.AppendFile.txt")
+          executableStat <- Fs.statFuture("x.AppendFile.sh")
+          _              <- Fs.unlinkFuture("x.AppendFile.txt")
+          _              <- Fs.unlinkFuture("x.AppendFile.sh")
+        } yield {
+          assert((defaultStat.mode & Fs.constants.R_OK) > 0)
+          assert((defaultStat.mode & Fs.constants.X_OK) === 0)
+          assert((executableStat.mode & Fs.constants.R_OK) === 0)
+          assert((executableStat.mode & Fs.constants.X_OK) > 0)
+          succeed
+        }
+      }
+    }
   }
 }