diff --git a/builder/proxmox/bootcommand_driver.go b/builder/proxmox/bootcommand_driver.go
index b8debaafb..4eeb48f5f 100644
--- a/builder/proxmox/bootcommand_driver.go
+++ b/builder/proxmox/bootcommand_driver.go
@@ -11,14 +11,14 @@ import (
 )
 
 type proxmoxDriver struct {
-	client     *proxmox.Client
+	client     commandTyper
 	vmRef      *proxmox.VmRef
 	specialMap map[string]string
 	runeMap    map[rune]string
 	interval   time.Duration
 }
 
-func NewProxmoxDriver(c *proxmox.Client, vmRef *proxmox.VmRef, interval time.Duration) *proxmoxDriver {
+func NewProxmoxDriver(c commandTyper, vmRef *proxmox.VmRef, interval time.Duration) *proxmoxDriver {
 	// Mappings for packer shorthand to qemu qkeycodes
 	sMap := map[string]string{
 		"spacebar": "spc",
@@ -90,7 +90,7 @@ func (p *proxmoxDriver) SendKey(key rune, action bootcommand.KeyAction) error {
 
 	var keys string
 	if keyShift {
-		keys = fmt.Sprintf(shiftFormat, key)
+		keys = fmt.Sprintf(shiftFormat, unicode.ToLower(key))
 	} else {
 		keys = fmt.Sprintf("%c", key)
 	}
diff --git a/builder/proxmox/step_type_boot_command.go b/builder/proxmox/step_type_boot_command.go
index f76cd5e52..1967b09ca 100644
--- a/builder/proxmox/step_type_boot_command.go
+++ b/builder/proxmox/step_type_boot_command.go
@@ -28,10 +28,14 @@ type bootCommandTemplateData struct {
 	HTTPPort uint
 }
 
+type commandTyper interface {
+	MonitorCmd(*proxmox.VmRef, string) (map[string]interface{}, error)
+}
+
 func (s *stepTypeBootCommand) Run(ctx context.Context, state multistep.StateBag) multistep.StepAction {
 	ui := state.Get("ui").(packer.Ui)
 	c := state.Get("config").(*Config)
-	client := state.Get("proxmoxClient").(*proxmox.Client)
+	client := state.Get("proxmoxClient").(commandTyper)
 	vmRef := state.Get("vmRef").(*proxmox.VmRef)
 
 	if len(s.BootCommand) == 0 {
diff --git a/builder/proxmox/step_type_boot_command_test.go b/builder/proxmox/step_type_boot_command_test.go
new file mode 100644
index 000000000..efe8b4c4c
--- /dev/null
+++ b/builder/proxmox/step_type_boot_command_test.go
@@ -0,0 +1,124 @@
+package proxmox
+
+import (
+	"context"
+	"fmt"
+	"strings"
+	"testing"
+
+	"github.com/Telmate/proxmox-api-go/proxmox"
+	"github.com/hashicorp/packer/common/bootcommand"
+	"github.com/hashicorp/packer/helper/multistep"
+	"github.com/hashicorp/packer/packer"
+)
+
+type commandTyperMock struct {
+	monitorCmd func(*proxmox.VmRef, string) (map[string]interface{}, error)
+}
+
+func (m commandTyperMock) MonitorCmd(ref *proxmox.VmRef, cmd string) (map[string]interface{}, error) {
+	return m.monitorCmd(ref, cmd)
+}
+
+func TestTypeBootCommand(t *testing.T) {
+	cs := []struct {
+		name                 string
+		builderConfig        *Config
+		expectCallMonitorCmd bool
+		monitorCmdErr        error
+		monitorCmdRet        map[string]interface{}
+		expectedKeysSent     string
+		expectedAction       multistep.StepAction
+	}{
+		{
+			name:                 "simple boot command is typed",
+			builderConfig:        &Config{BootConfig: bootcommand.BootConfig{BootCommand: []string{"hello"}}},
+			expectCallMonitorCmd: true,
+			expectedKeysSent:     "hello",
+			expectedAction:       multistep.ActionContinue,
+		},
+		{
+			name:                 "interpolated boot command",
+			builderConfig:        &Config{BootConfig: bootcommand.BootConfig{BootCommand: []string{"hello<enter>world"}}},
+			expectCallMonitorCmd: true,
+			expectedKeysSent:     "helloretworld",
+			expectedAction:       multistep.ActionContinue,
+		},
+		{
+			name:                 "merge multiple interpolated boot command",
+			builderConfig:        &Config{BootConfig: bootcommand.BootConfig{BootCommand: []string{"Hello World 2.0", "foo!bar@baz"}}},
+			expectCallMonitorCmd: true,
+			expectedKeysSent:     "shift-hellospcshift-worldspc2dot0fooshift-1barshift-2baz",
+			expectedAction:       multistep.ActionContinue,
+		},
+		{
+			name:                 "without boot command monitorcmd should not be called",
+			builderConfig:        &Config{BootConfig: bootcommand.BootConfig{BootCommand: []string{}}},
+			expectCallMonitorCmd: false,
+			expectedAction:       multistep.ActionContinue,
+		},
+		{
+			name:                 "invalid boot command template function",
+			builderConfig:        &Config{BootConfig: bootcommand.BootConfig{BootCommand: []string{"{{ foo }}"}}},
+			expectCallMonitorCmd: false,
+			expectedAction:       multistep.ActionHalt,
+		},
+		{
+			// When proxmox (or Qemu, really) doesn't recognize the keycode we send, we get no error back, but
+			// a map {"data": "invalid parameter: X"}, where X is the keycode.
+			name:                 "invalid keys sent to proxmox",
+			builderConfig:        &Config{BootConfig: bootcommand.BootConfig{BootCommand: []string{"x"}}},
+			expectCallMonitorCmd: true,
+			monitorCmdRet:        map[string]interface{}{"data": "invalid parameter: x"},
+			expectedKeysSent:     "x",
+			expectedAction:       multistep.ActionHalt,
+		},
+		{
+			name:                 "error in typing should return halt",
+			builderConfig:        &Config{BootConfig: bootcommand.BootConfig{BootCommand: []string{"hello"}}},
+			expectCallMonitorCmd: true,
+			monitorCmdErr:        fmt.Errorf("some error"),
+			expectedKeysSent:     "h",
+			expectedAction:       multistep.ActionHalt,
+		},
+	}
+
+	for _, c := range cs {
+		t.Run(c.name, func(t *testing.T) {
+			accumulator := strings.Builder{}
+			typer := commandTyperMock{
+				monitorCmd: func(ref *proxmox.VmRef, cmd string) (map[string]interface{}, error) {
+					if !c.expectCallMonitorCmd {
+						t.Error("Did not expect MonitorCmd to be called")
+					}
+					if !strings.HasPrefix(cmd, "sendkey ") {
+						t.Errorf("Expected all commands to be sendkey, got %s", cmd)
+					}
+
+					accumulator.WriteString(strings.TrimPrefix(cmd, "sendkey "))
+
+					return c.monitorCmdRet, c.monitorCmdErr
+				},
+			}
+
+			state := new(multistep.BasicStateBag)
+			state.Put("ui", packer.TestUi(t))
+			state.Put("config", c.builderConfig)
+			state.Put("http_port", uint(0))
+			state.Put("vmRef", proxmox.NewVmRef(1))
+			state.Put("proxmoxClient", typer)
+
+			step := stepTypeBootCommand{
+				c.builderConfig.BootConfig,
+				c.builderConfig.ctx,
+			}
+			action := step.Run(context.TODO(), state)
+			if action != c.expectedAction {
+				t.Errorf("Expected action to be %v, got %v", c.expectedAction, action)
+			}
+			if c.expectedKeysSent != accumulator.String() {
+				t.Errorf("Expected keystrokes to be %q, got %q", c.expectedKeysSent, accumulator.String())
+			}
+		})
+	}
+}