diff --git a/device/queueconstants_android.go b/device/queueconstants_android.go
new file mode 100644
index 0000000..8d051ad
--- /dev/null
+++ b/device/queueconstants_android.go
@@ -0,0 +1,16 @@
+/* SPDX-License-Identifier: MIT
+ *
+ * Copyright (C) 2017-2019 WireGuard LLC. All Rights Reserved.
+ */
+
+package device
+
+/* Reduce memory consumption for Android */
+
+const (
+	QueueOutboundSize          = 1024
+	QueueInboundSize           = 1024
+	QueueHandshakeSize         = 1024
+	MaxSegmentSize             = 2200
+	PreallocatedBuffersPerPool = 4096
+)
\ No newline at end of file
diff --git a/device/queueconstants.go b/device/queueconstants_default.go
similarity index 90%
rename from device/queueconstants.go
rename to device/queueconstants_default.go
index 3e94b7f..cf86ba1 100644
--- a/device/queueconstants.go
+++ b/device/queueconstants_default.go
@@ -1,3 +1,5 @@
+// +build !android,!ios
+
 /* SPDX-License-Identifier: MIT
  *
  * Copyright (C) 2017-2019 WireGuard LLC. All Rights Reserved.
@@ -5,8 +7,6 @@
 
 package device
 
-/* Implementation specific constants */
-
 const (
 	QueueOutboundSize          = 1024
 	QueueInboundSize           = 1024
diff --git a/device/queueconstants_ios.go b/device/queueconstants_ios.go
new file mode 100644
index 0000000..589b0aa
--- /dev/null
+++ b/device/queueconstants_ios.go
@@ -0,0 +1,18 @@
+// +build ios
+
+/* SPDX-License-Identifier: MIT
+ *
+ * Copyright (C) 2017-2019 WireGuard LLC. All Rights Reserved.
+ */
+
+package device
+
+/* Fit within memory limits for iOS's Network Extension API, which has stricter requirements */
+
+const (
+	QueueOutboundSize          = 1024
+	QueueInboundSize           = 1024
+	QueueHandshakeSize         = 1024
+	MaxSegmentSize             = 1700
+	PreallocatedBuffersPerPool = 1024
+)
diff --git a/tun/tun_darwin.go b/tun/tun_darwin.go
index 600b156..3b39982 100644
--- a/tun/tun_darwin.go
+++ b/tun/tun_darwin.go
@@ -171,7 +171,7 @@ func CreateTUNFromFile(file *os.File, mtu int) (TUNDevice, error) {
 	tun := &NativeTun{
 		tunFile: file,
 		events:  make(chan TUNEvent, 10),
-		errors:  make(chan error, 1),
+		errors:  make(chan error, 5),
 	}
 
 	name, err := tun.Name()
@@ -200,10 +200,12 @@ func CreateTUNFromFile(file *os.File, mtu int) (TUNDevice, error) {
 
 	go tun.routineRouteListener(tunIfindex)
 
-	err = tun.setMTU(mtu)
-	if err != nil {
-		tun.Close()
-		return nil, err
+	if mtu > 0 {
+		err = tun.setMTU(mtu)
+		if err != nil {
+			tun.Close()
+			return nil, err
+		}
 	}
 
 	return tun, nil
diff --git a/tun/tun_linux.go b/tun/tun_linux.go
index f808079..c352c1a 100644
--- a/tun/tun_linux.go
+++ b/tun/tun_linux.go
@@ -443,3 +443,25 @@ func CreateTUNFromFile(file *os.File, mtu int) (TUNDevice, error) {
 
 	return tun, nil
 }
+
+func CreateUnmonitoredTUNFromFD(tunFd int) (TUNDevice, string, error) {
+	file := os.NewFile(uintptr(tunFd), "/dev/tun")
+	tun := &NativeTun{
+		tunFile: file,
+		fd:      file.Fd(),
+		events:  make(chan TUNEvent, 5),
+		errors:  make(chan error, 5),
+		nopi:    true,
+	}
+	var err error
+	tun.fdCancel, err = rwcancel.NewRWCancel(int(tun.fd))
+	if err != nil {
+		return nil, "", err
+	}
+	name, err := tun.Name()
+	if err != nil {
+		tun.fdCancel.Cancel()
+		return nil, "", err
+	}
+	return tun, name, nil
+}