diff --git a/google/resource_compute_instance_group_manager.go b/google/resource_compute_instance_group_manager.go
index f5068640bbd..14a91afb268 100644
--- a/google/resource_compute_instance_group_manager.go
+++ b/google/resource_compute_instance_group_manager.go
@@ -144,8 +144,7 @@ func resourceComputeInstanceGroupManager() *schema.Resource {
 
 			"update_strategy": {
 				Type:     schema.TypeString,
-				Optional: true,
-				Default:  "REPLACE",
+				Computed: true,
 				Removed:  "This field has been replaced by `update_policy`",
 			},
 
diff --git a/google/resource_compute_region_instance_group_manager.go b/google/resource_compute_region_instance_group_manager.go
index 2f4cc6d7232..d2e57bd417d 100644
--- a/google/resource_compute_region_instance_group_manager.go
+++ b/google/resource_compute_region_instance_group_manager.go
@@ -38,7 +38,7 @@ func resourceComputeRegionInstanceGroupManager() *schema.Resource {
 
 			"instance_template": {
 				Type:     schema.TypeString,
-				Optional: true,
+				Computed: true,
 				Removed:  "This field has been replaced by `version.instance_template` in 3.0.0",
 			},