diff --git a/decort/resource_compute.go b/decort/resource_compute.go
index f2a73a4..c821cef 100644
--- a/decort/resource_compute.go
+++ b/decort/resource_compute.go
@@ -392,6 +392,7 @@ func resourceCompute() *schema.Resource {
 				Type:        schema.TypeInt,
 				Required:    true,
 				ForceNew:    true,
+				ValidateFunc: validation.IntAtLeast(1),
 				Description: "ID of the OS image to base this compute instance on.",
 			},