diff --git a/scaleway/resource_instance_volume.go b/scaleway/resource_instance_volume.go
index 5425b1d416..74b7535fdc 100644
--- a/scaleway/resource_instance_volume.go
+++ b/scaleway/resource_instance_volume.go
@@ -38,6 +38,7 @@ func resourceScalewayInstanceVolume() *schema.Resource {
 			},
 			"size_in_gb": {
 				Type:          schema.TypeInt,
+				Computed:      true,
 				Optional:      true,
 				ForceNew:      true,
 				Description:   "The size of the volume in gigabyte",