diff --git a/client/vif.go b/client/vif.go
index 0486dc42..418023dd 100644
--- a/client/vif.go
+++ b/client/vif.go
@@ -74,7 +74,9 @@ func (c *Client) CreateVIF(vm *Vm, vif *VIF) (*VIF, error) {
 	params := map[string]interface{}{
 		"network": vif.Network,
 		"vm":      vm.Id,
-		"mac":     vif.MacAddress,
+	}
+	if vif.MacAddress != "" {
+		params["mac"] = vif.MacAddress
 	}
 	err := c.Call("vm.createInterface", params, &id)
 
diff --git a/client/vm.go b/client/vm.go
index a492e7cd..a3520f7b 100644
--- a/client/vm.go
+++ b/client/vm.go
@@ -95,7 +95,7 @@ type Vm struct {
 	Boot               Boot              `json:"boot,omitempty"`
 	Type               string            `json:"type,omitempty"`
 	Id                 string            `json:"id,omitempty"`
-	AffinityHost       string            `json:"affinityHost,omitempty"`
+	AffinityHost       *string           `json:"affinityHost,omitempty"`
 	NameDescription    string            `json:"name_description"`
 	NameLabel          string            `json:"name_label"`
 	CPUs               CPUs              `json:"CPUs"`
@@ -212,7 +212,6 @@ func (c *Client) CreateVm(vmReq Vm, createTime time.Duration) (*Vm, error) {
 	}
 
 	params := map[string]interface{}{
-		"affinityHost":     vmReq.AffinityHost,
 		"bootAfterCreate":  true,
 		"name_label":       vmReq.NameLabel,
 		"name_description": vmReq.NameDescription,
@@ -243,6 +242,11 @@ func (c *Client) CreateVm(vmReq Vm, createTime time.Duration) (*Vm, error) {
 		params["hvmBootFirmware"] = firmware
 	}
 
+	affinityHost := vmReq.AffinityHost
+	if affinityHost != nil {
+		params["affinityHost"] = affinityHost
+	}
+
 	vga := vmReq.Vga
 	if vga != "" {
 		params["vga"] = vga
@@ -319,7 +323,6 @@ func createVdiMap(disk Disk) map[string]interface{} {
 func (c *Client) UpdateVm(vmReq Vm) (*Vm, error) {
 	params := map[string]interface{}{
 		"id":                vmReq.Id,
-		"affinityHost":      vmReq.AffinityHost,
 		"name_label":        vmReq.NameLabel,
 		"name_description":  vmReq.NameDescription,
 		"auto_poweron":      vmReq.AutoPoweron,
@@ -341,6 +344,15 @@ func (c *Client) UpdateVm(vmReq Vm) (*Vm, error) {
 		// coresPerSocket is null or a number of cores per socket. Putting an invalid value doesn't seem to cause an error :(
 	}
 
+	affinityHost := vmReq.AffinityHost
+	if affinityHost != nil {
+		if *affinityHost == "" {
+			params["affinityHost"] = nil
+		} else {
+			params["affinityHost"] = *affinityHost
+		}
+	}
+
 	videoram := vmReq.Videoram.Value
 	if videoram != 0 {
 		params["videoram"] = videoram
diff --git a/xoa/resource_xenorchestra_vm.go b/xoa/resource_xenorchestra_vm.go
index d9d77a85..3c716e08 100644
--- a/xoa/resource_xenorchestra_vm.go
+++ b/xoa/resource_xenorchestra_vm.go
@@ -407,8 +407,7 @@ func resourceVmCreate(d *schema.ResourceData, m interface{}) error {
 			Id: rsId.(string),
 		}
 	}
-	vm, err := c.CreateVm(client.Vm{
-		AffinityHost:      d.Get("affinity_host").(string),
+	createVmParams := client.Vm{
 		BlockedOperations: blockedOperations,
 		Boot: client.Boot{
 			Firmware: d.Get("hvm_boot_firmware").(string),
@@ -442,9 +441,13 @@ func resourceVmCreate(d *schema.ResourceData, m interface{}) error {
 			Value: d.Get("videoram").(int),
 		},
 		Vga: d.Get("vga").(string),
-	},
-		d.Timeout(schema.TimeoutCreate),
-	)
+	}
+
+	affinityHost := d.Get("affinity_host").(string)
+	if affinityHost != "" {
+		createVmParams.AffinityHost = &affinityHost
+	}
+	vm, err := c.CreateVm(createVmParams, d.Timeout(schema.TimeoutCreate))
 
 	if err != nil {
 		return err
@@ -780,7 +783,6 @@ func resourceVmUpdate(d *schema.ResourceData, m interface{}) error {
 		HA:                ha,
 		ResourceSet:       rs,
 		AutoPoweron:       autoPowerOn,
-		AffinityHost:      affinityHost,
 		BlockedOperations: blockOperations,
 		ExpNestedHvm:      d.Get("exp_nested_hvm").(bool),
 		StartDelay:        d.Get("start_delay").(int),
@@ -794,6 +796,11 @@ func resourceVmUpdate(d *schema.ResourceData, m interface{}) error {
 			Value: d.Get("videoram").(int),
 		},
 	}
+
+	if d.HasChange("affinity_host") {
+		vmReq.AffinityHost = &affinityHost
+	}
+
 	if haltForUpdates {
 		err := c.HaltVm(id)