diff --git a/builder/proxmox/common/config.go b/builder/proxmox/common/config.go
index 88a6ef79..5aa86663 100644
--- a/builder/proxmox/common/config.go
+++ b/builder/proxmox/common/config.go
@@ -363,6 +363,10 @@ type diskConfig struct {
 type efiConfig struct {
 	// Name of the Proxmox storage pool to store the EFI disk on.
 	EFIStoragePool string `mapstructure:"efi_storage_pool"`
+	// The format of the file backing the disk. Can be
+	// `raw`, `cow`, `qcow`, `qed`, `qcow2`, `vmdk` or `cloop`. Defaults to
+	// `raw`.
+	EFIFormat string `mapstructure:"efi_format"`
 	// Whether Microsoft Standard Secure Boot keys should be pre-loaded on
 	// the EFI disk. Defaults to `false`.
 	PreEnrolledKeys bool `mapstructure:"pre_enrolled_keys"`
diff --git a/builder/proxmox/common/config.hcl2spec.go b/builder/proxmox/common/config.hcl2spec.go
index e5cf36f9..2f50e823 100644
--- a/builder/proxmox/common/config.hcl2spec.go
+++ b/builder/proxmox/common/config.hcl2spec.go
@@ -367,6 +367,7 @@ func (*FlatdiskConfig) HCL2Spec() map[string]hcldec.Spec {
 // Where the contents of a field with a `mapstructure:,squash` tag are bubbled up.
 type FlatefiConfig struct {
 	EFIStoragePool  *string `mapstructure:"efi_storage_pool" cty:"efi_storage_pool" hcl:"efi_storage_pool"`
+	EFIFormat       *string `mapstructure:"efi_format" cty:"efi_format" hcl:"efi_format"`
 	PreEnrolledKeys *bool   `mapstructure:"pre_enrolled_keys" cty:"pre_enrolled_keys" hcl:"pre_enrolled_keys"`
 	EFIType         *string `mapstructure:"efi_type" cty:"efi_type" hcl:"efi_type"`
 }
@@ -384,6 +385,7 @@ func (*efiConfig) FlatMapstructure() interface{ HCL2Spec() map[string]hcldec.Spe
 func (*FlatefiConfig) HCL2Spec() map[string]hcldec.Spec {
 	s := map[string]hcldec.Spec{
 		"efi_storage_pool":  &hcldec.AttrSpec{Name: "efi_storage_pool", Type: cty.String, Required: false},
+		"efi_format":        &hcldec.AttrSpec{Name: "efi_format", Type: cty.String, Required: false},
 		"pre_enrolled_keys": &hcldec.AttrSpec{Name: "pre_enrolled_keys", Type: cty.Bool, Required: false},
 		"efi_type":          &hcldec.AttrSpec{Name: "efi_type", Type: cty.String, Required: false},
 	}
diff --git a/builder/proxmox/common/step_start_vm.go b/builder/proxmox/common/step_start_vm.go
index 4c9bd859..950b906d 100644
--- a/builder/proxmox/common/step_start_vm.go
+++ b/builder/proxmox/common/step_start_vm.go
@@ -363,6 +363,7 @@ func generateProxmoxEfi(efi efiConfig) proxmox.QemuDevice {
 	dev := make(proxmox.QemuDevice)
 	setDeviceParamIfDefined(dev, "storage", efi.EFIStoragePool)
 	setDeviceParamIfDefined(dev, "efitype", efi.EFIType)
+	setDeviceParamIfDefined(dev, "format", efi.EFIFormat)
 	// efi.PreEnrolledKeys can be false, but we only want to set pre-enrolled-keys=0
 	// when other EFI options are set.
 	if len(dev) > 0 {
diff --git a/docs-partials/builder/proxmox/common/efiConfig-not-required.mdx b/docs-partials/builder/proxmox/common/efiConfig-not-required.mdx
index 8ed6dd8d..ae133299 100644
--- a/docs-partials/builder/proxmox/common/efiConfig-not-required.mdx
+++ b/docs-partials/builder/proxmox/common/efiConfig-not-required.mdx
@@ -2,6 +2,9 @@
 
 - `efi_storage_pool` (string) - Name of the Proxmox storage pool to store the EFI disk on.
 
+- `efi_format` (string) - The format of the file backing the disk. Can be
+  `raw`, `cow`, `qcow`, `qed`, `qcow2`, `vmdk` or `cloop`. Defaults to `raw`.
+
 - `pre_enrolled_keys` (bool) - Whether Microsoft Standard Secure Boot keys should be pre-loaded on
   the EFI disk. Defaults to `false`.
 
diff --git a/docs-partials/builder/proxmox/common/efiConfig.mdx b/docs-partials/builder/proxmox/common/efiConfig.mdx
index ff092043..f6d7dd0c 100644
--- a/docs-partials/builder/proxmox/common/efiConfig.mdx
+++ b/docs-partials/builder/proxmox/common/efiConfig.mdx
@@ -10,6 +10,7 @@ Usage example (JSON):
 	{
 	  "efi_storage_pool": "local",
 	  "pre_enrolled_keys": true,
+	  "efi_format": "raw",
 	  "efi_type": "4m"
 	}