diff --git a/driver/vm.go b/driver/vm.go
index 0171ac606..690d40869 100644
--- a/driver/vm.go
+++ b/driver/vm.go
@@ -81,11 +81,13 @@ func (d *Driver) CreateVM(config *CreateConfig) (*VirtualMachine, error) {
 		Name:       config.Name,
 		Annotation: config.Annotation,
 		GuestId:    config.GuestOS,
-		Firmware:   config.Firmware,
 	}
 	if config.Version != 0 {
 		createSpec.Version = fmt.Sprintf("%s%d", "vmx-", config.Version)
 	}
+	if config.Firmware != "" {
+		createSpec.Firmware = config.Firmware
+	}
 
 	folder, err := d.FindFolder(config.Folder)
 	if err != nil {
diff --git a/iso/builder_acc_test.go b/iso/builder_acc_test.go
index 5f4c6de89..6d2ceec6a 100644
--- a/iso/builder_acc_test.go
+++ b/iso/builder_acc_test.go
@@ -45,7 +45,7 @@ func checkDefault(t *testing.T, name string, host string, datastore string) buil
 		d := commonT.TestConn(t)
 		vm := commonT.GetVM(t, d, artifacts)
 
-		vmInfo, err := vm.Info("name", "parent", "runtime.host", "resourcePool", "datastore", "layoutEx.disk")
+		vmInfo, err := vm.Info("name", "parent", "runtime.host", "resourcePool", "datastore", "layoutEx.disk", "config.firmware")
 		if err != nil {
 			t.Fatalf("Cannot read VM properties: %v", err)
 		}
@@ -91,6 +91,11 @@ func checkDefault(t *testing.T, name string, host string, datastore string) buil
 			t.Errorf("Invalid datastore name: expected '%v', got '%v'", datastore, dsInfo.Name)
 		}
 
+		fw := vmInfo.Config.Firmware
+		if fw != "bios" {
+			t.Errorf("Invalid firmware: expected 'bios', got '%v'", fw)
+		}
+
 		return nil
 	}
 }
@@ -111,6 +116,7 @@ func hardwareConfig() string {
 	config["RAM"] = 2048
 	config["RAM_reservation"] = 1024
 	config["NestedHV"] = true
+	config["firmware"] = "efi"
 
 	return commonT.RenderConfig(config)
 }
@@ -155,6 +161,11 @@ func checkHardware(t *testing.T) builderT.TestCheckFunc {
 			t.Errorf("VM should have NestedHV enabled, got %v", nestedHV)
 		}
 
+		fw := vmInfo.Config.Firmware
+		if fw != "efi" {
+			t.Errorf("Invalid firmware: expected 'efi', got '%v'", fw)
+		}
+
 		return nil
 	}
 }
diff --git a/iso/step_create.go b/iso/step_create.go
index 5a23bd535..39d448b55 100644
--- a/iso/step_create.go
+++ b/iso/step_create.go
@@ -34,8 +34,8 @@ func (c *CreateConfig) Prepare() []error {
 		c.GuestOSType = "otherGuest"
 	}
 
-	if (c.Firmware == "") {
-		c.Firmware = "bios"
+	if (c.Firmware != "" && c.Firmware != "bios" && c.Firmware != "efi") {
+		errs = append(errs, fmt.Errorf("'firmware' must be 'bios' or 'efi'"))
 	}
 
 	return errs