diff --git a/packer/rpc/ui.go b/packer/rpc/ui.go
index 6d69ca244..2a3807528 100644
--- a/packer/rpc/ui.go
+++ b/packer/rpc/ui.go
@@ -17,6 +17,12 @@ type UiServer struct {
 	ui packer.Ui
 }
 
+// The arguments sent to Ui.Machine
+type UiMachineArgs struct {
+	category string
+	args     []string
+}
+
 func (u *Ui) Ask(query string) (result string, err error) {
 	err = u.client.Call("Ui.Ask", query, &result)
 	return
@@ -28,6 +34,17 @@ func (u *Ui) Error(message string) {
 	}
 }
 
+func (u *Ui) Machine(t string, args ...string) {
+	rpcArgs := &UiMachineArgs{
+		category: t,
+		args:     args,
+	}
+
+	if err := u.client.Call("Ui.Message", rpcArgs, new(interface{})); err != nil {
+		panic(err)
+	}
+}
+
 func (u *Ui) Message(message string) {
 	if err := u.client.Call("Ui.Message", message, new(interface{})); err != nil {
 		panic(err)
@@ -52,6 +69,13 @@ func (u *UiServer) Error(message *string, reply *interface{}) error {
 	return nil
 }
 
+func (u *UiServer) Machine(args *UiMachineArgs, reply *interface{}) error {
+	u.ui.Machine(args.category, args.args...)
+
+	*reply = nil
+	return nil
+}
+
 func (u *UiServer) Message(message *string, reply *interface{}) error {
 	u.ui.Message(*message)
 	*reply = nil
diff --git a/packer/rpc/ui_test.go b/packer/rpc/ui_test.go
index 78c203540..7dae40763 100644
--- a/packer/rpc/ui_test.go
+++ b/packer/rpc/ui_test.go
@@ -11,6 +11,9 @@ type testUi struct {
 	askQuery       string
 	errorCalled    bool
 	errorMessage   string
+	machineCalled  bool
+	machineType    string
+	machineArgs    []string
 	messageCalled  bool
 	messageMessage string
 	sayCalled      bool
@@ -28,6 +31,12 @@ func (u *testUi) Error(message string) {
 	u.errorMessage = message
 }
 
+func (u *testUi) Machine(t string, args ...string) {
+	u.machineCalled = true
+	u.machineType = t
+	u.machineArgs = args
+}
+
 func (u *testUi) Message(message string) {
 	u.messageCalled = true
 	u.messageMessage = message
diff --git a/packer/ui.go b/packer/ui.go
index f19ebc04b..5d5ca1065 100644
--- a/packer/ui.go
+++ b/packer/ui.go
@@ -33,6 +33,7 @@ type Ui interface {
 	Say(string)
 	Message(string)
 	Error(string)
+	Machine(string, ...string)
 }
 
 // ColoredUi is a UI that is colored using terminal colors.
@@ -80,6 +81,11 @@ func (u *ColoredUi) Error(message string) {
 	u.Ui.Error(u.colorize(message, color, true))
 }
 
+func (u *ColoredUi) Machine(t string, args ...string) {
+	// Don't colorize machine-readable output
+	u.Ui.Machine(t, args...)
+}
+
 func (u *ColoredUi) colorize(message string, color UiColor, bold bool) string {
 	if !u.supportsColors() {
 		return message
@@ -123,6 +129,11 @@ func (u *PrefixedUi) Error(message string) {
 	u.Ui.Error(u.prefixLines(u.SayPrefix, message))
 }
 
+func (u *PrefixedUi) Machine(t string, args ...string) {
+	// Just pass it through for now.
+	u.Ui.Machine(t, args...)
+}
+
 func (u *PrefixedUi) prefixLines(prefix, message string) string {
 	var result bytes.Buffer
 
@@ -209,3 +220,7 @@ func (rw *ReaderWriterUi) Error(message string) {
 		panic(err)
 	}
 }
+
+func (rw *ReaderWriterUi) Machine(t string, args ...string) {
+	// TODO
+}
diff --git a/provisioner/file/provisioner_test.go b/provisioner/file/provisioner_test.go
index 9c57ac452..c35f67cdb 100644
--- a/provisioner/file/provisioner_test.go
+++ b/provisioner/file/provisioner_test.go
@@ -106,6 +106,9 @@ func (su *stubUi) Ask(string) (string, error) {
 func (su *stubUi) Error(string) {
 }
 
+func (su *stubUi) Machine(string, ...string) {
+}
+
 func (su *stubUi) Message(string) {
 }