diff --git a/packer/build.go b/packer/build.go
index d2502625a..97d6d5f8a 100644
--- a/packer/build.go
+++ b/packer/build.go
@@ -52,7 +52,7 @@ func (b *coreBuild) Prepare(ui Ui) (err error) {
 	// Prepare the provisioners
 	// TODO: error handling
 	for _, coreProv := range b.provisioners {
-		coreProv.provisioner.Prepare(coreProv.config, ui)
+		coreProv.provisioner.Prepare(coreProv.config)
 	}
 
 	return
diff --git a/packer/build_test.go b/packer/build_test.go
index a8870a59a..fb748561c 100644
--- a/packer/build_test.go
+++ b/packer/build_test.go
@@ -47,8 +47,7 @@ func TestBuild_Prepare(t *testing.T) {
 	coreProv := coreB.provisioners[0]
 	prov := coreProv.provisioner.(*TestProvisioner)
 	assert.True(prov.prepCalled, "prepare should be called")
-	assert.Equal(prov.prepConfig, 42, "prepare should be called with proper config")
-	assert.Equal(prov.prepUi, ui, "prepare should be called with proper ui")
+	assert.Equal(prov.prepConfigs, []interface{}{42}, "prepare should be called with proper config")
 }
 
 func TestBuild_Run(t *testing.T) {
diff --git a/packer/plugin/provisioner.go b/packer/plugin/provisioner.go
index 93e6fb1bb..3655bb798 100644
--- a/packer/plugin/provisioner.go
+++ b/packer/plugin/provisioner.go
@@ -13,13 +13,13 @@ type cmdProvisioner struct {
 	client *client
 }
 
-func (c *cmdProvisioner) Prepare(config interface{}, ui packer.Ui) {
+func (c *cmdProvisioner) Prepare(configs ...interface{}) {
 	defer func() {
 		r := recover()
 		c.checkExit(r, nil)
 	}()
 
-	c.p.Prepare(config, ui)
+	c.p.Prepare(configs...)
 }
 
 func (c *cmdProvisioner) Provision(ui packer.Ui, comm packer.Communicator) {
diff --git a/packer/plugin/provisioner_test.go b/packer/plugin/provisioner_test.go
index 39d489360..dc0bb4d88 100644
--- a/packer/plugin/provisioner_test.go
+++ b/packer/plugin/provisioner_test.go
@@ -9,7 +9,7 @@ import (
 
 type helperProvisioner byte
 
-func (helperProvisioner) Prepare(interface{}, packer.Ui) {}
+func (helperProvisioner) Prepare(...interface{}) {}
 
 func (helperProvisioner) Provision(packer.Ui, packer.Communicator) {}
 
diff --git a/packer/provisioner.go b/packer/provisioner.go
index 07a2052f0..db389eddb 100644
--- a/packer/provisioner.go
+++ b/packer/provisioner.go
@@ -6,7 +6,7 @@ type Provisioner interface {
 	// Prepare is called with the raw configuration and a UI element in
 	// order to setup the internal state of the provisioner and perform
 	// any validation necessary for the provisioner.
-	Prepare(interface{}, Ui)
+	Prepare(...interface{})
 
 	// Provision is called to actually provision the machine. A UI is
 	// given to communicate with the user, and a communicator is given that
diff --git a/packer/provisioner_test.go b/packer/provisioner_test.go
index 08133fcdc..cf800e4d6 100644
--- a/packer/provisioner_test.go
+++ b/packer/provisioner_test.go
@@ -4,15 +4,13 @@ import "testing"
 
 type TestProvisioner struct {
 	prepCalled bool
-	prepConfig interface{}
-	prepUi     Ui
+	prepConfigs []interface{}
 	provCalled bool
 }
 
-func (t *TestProvisioner) Prepare(config interface{}, ui Ui) {
+func (t *TestProvisioner) Prepare(configs ...interface{}) {
 	t.prepCalled = true
-	t.prepConfig = config
-	t.prepUi = ui
+	t.prepConfigs = configs
 }
 
 func (t *TestProvisioner) Provision(Ui, Communicator) {
diff --git a/packer/rpc/provisioner.go b/packer/rpc/provisioner.go
index 027667d8e..e66a974c5 100644
--- a/packer/rpc/provisioner.go
+++ b/packer/rpc/provisioner.go
@@ -18,8 +18,7 @@ type ProvisionerServer struct {
 }
 
 type ProvisionerPrepareArgs struct {
-	Config     interface{}
-	RPCAddress string
+	Configs     []interface{}
 }
 
 type ProvisionerProvisionArgs struct {
@@ -29,12 +28,8 @@ type ProvisionerProvisionArgs struct {
 func Provisioner(client *rpc.Client) *provisioner {
 	return &provisioner{client}
 }
-func (p *provisioner) Prepare(config interface{}, ui packer.Ui) {
-	// TODO: Error handling
-	server := rpc.NewServer()
-	RegisterUi(server, ui)
-
-	args := &ProvisionerPrepareArgs{config, serveSingleConn(server)}
+func (p *provisioner) Prepare(configs ...interface{}) {
+	args := &ProvisionerPrepareArgs{configs}
 	p.client.Call("Provisioner.Prepare", args, new(interface{}))
 }
 
@@ -49,14 +44,7 @@ func (p *provisioner) Provision(ui packer.Ui, comm packer.Communicator) {
 }
 
 func (p *ProvisionerServer) Prepare(args *ProvisionerPrepareArgs, reply *interface{}) error {
-	client, err := rpc.Dial("tcp", args.RPCAddress)
-	if err != nil {
-		return err
-	}
-
-	ui := &Ui{client}
-
-	p.p.Prepare(args.Config, ui)
+	p.p.Prepare(args.Configs...)
 	return nil
 }
 
diff --git a/packer/rpc/provisioner_test.go b/packer/rpc/provisioner_test.go
index e35019a18..c8dc1a696 100644
--- a/packer/rpc/provisioner_test.go
+++ b/packer/rpc/provisioner_test.go
@@ -9,17 +9,15 @@ import (
 
 type testProvisioner struct {
 	prepareCalled bool
-	prepareConfig interface{}
-	prepareUi     packer.Ui
+	prepareConfigs []interface{}
 	provCalled    bool
 	provComm      packer.Communicator
 	provUi        packer.Ui
 }
 
-func (p *testProvisioner) Prepare(config interface{}, ui packer.Ui) {
+func (p *testProvisioner) Prepare(configs ...interface{}) {
 	p.prepareCalled = true
-	p.prepareConfig = config
-	p.prepareUi = ui
+	p.prepareConfigs = configs
 }
 
 func (p *testProvisioner) Provision(ui packer.Ui, comm packer.Communicator) {
@@ -45,17 +43,13 @@ func TestProvisionerRPC(t *testing.T) {
 
 	// Test Prepare
 	config := 42
-	ui := &testUi{}
 	pClient := Provisioner(client)
-	pClient.Prepare(config, ui)
+	pClient.Prepare(config)
 	assert.True(p.prepareCalled, "prepare should be called")
-	assert.Equal(p.prepareConfig, 42, "prepare should be called with right arg")
-
-	p.prepareUi.Say("foo")
-	assert.True(ui.sayCalled, "say should be called")
+	assert.Equal(p.prepareConfigs, []interface{}{42}, "prepare should be called with right arg")
 
 	// Test Provision
-	ui = &testUi{}
+	ui := &testUi{}
 	comm := &testCommunicator{}
 	pClient.Provision(ui, comm)
 	assert.True(p.provCalled, "provision should be called")
diff --git a/provisioner/shell/provisioner.go b/provisioner/shell/provisioner.go
index 170aba46d..74d31dd34 100644
--- a/provisioner/shell/provisioner.go
+++ b/provisioner/shell/provisioner.go
@@ -29,9 +29,11 @@ type Provisioner struct {
 	config config
 }
 
-func (p *Provisioner) Prepare(raw interface{}, ui packer.Ui) {
+func (p *Provisioner) Prepare(raws ...interface{}) {
 	// TODO: errors
-	_ = mapstructure.Decode(raw, &p.config)
+	for _, raw := range raws {
+		_ = mapstructure.Decode(raw, &p.config)
+	}
 
 	if p.config.RemotePath == "" {
 		p.config.RemotePath = DefaultRemotePath