diff --git a/google/resource_compute_instance_group_manager.go b/google/resource_compute_instance_group_manager.go
index 75f6795d..1f564589 100644
--- a/google/resource_compute_instance_group_manager.go
+++ b/google/resource_compute_instance_group_manager.go
@@ -132,7 +132,7 @@ func resourceComputeInstanceGroupManagerCreate(d *schema.ResourceData, meta inte
 		return err
 	}
 
-	var targetSize int64 = 0
+	targetSize := int64(0)
 	if v, ok := d.GetOk("target_size"); ok {
 		targetSize = int64(v.(int))
 	}
@@ -143,6 +143,7 @@ func resourceComputeInstanceGroupManagerCreate(d *schema.ResourceData, meta inte
 		BaseInstanceName: d.Get("base_instance_name").(string),
 		InstanceTemplate: d.Get("instance_template").(string),
 		TargetSize:       targetSize,
+		// Force send TargetSize to allow a value of 0.
 		ForceSendFields:  []string{"TargetSize"},
 	}
 
@@ -381,11 +382,10 @@ func resourceComputeInstanceGroupManagerUpdate(d *schema.ResourceData, meta inte
 		d.SetPartial("named_port")
 	}
 
-	// We won't ever see changes if target_size is unset
 	if d.HasChange("target_size") {
-		target_size := int64(d.Get("target_size").(int))
+		targetSize := int64(d.Get("target_size").(int))
 		op, err := config.clientCompute.InstanceGroupManagers.Resize(
-			project, d.Get("zone").(string), d.Id(), target_size).Do()
+			project, d.Get("zone").(string), d.Id(), targetSize).Do()
 		if err != nil {
 			return fmt.Errorf("Error updating InstanceGroupManager: %s", err)
 		}
diff --git a/google/resource_compute_instance_group_manager_test.go b/google/resource_compute_instance_group_manager_test.go
index e44620a0..c8a02b51 100644
--- a/google/resource_compute_instance_group_manager_test.go
+++ b/google/resource_compute_instance_group_manager_test.go
@@ -42,8 +42,8 @@ func TestAccInstanceGroupManager_basic(t *testing.T) {
 func TestAccInstanceGroupManager_targetSizeZero(t *testing.T) {
 	var manager compute.InstanceGroupManager
 
-	template := fmt.Sprintf("igm-test-%s", acctest.RandString(10))
-	igm := fmt.Sprintf("igm-test-%s", acctest.RandString(10))
+	templateName := fmt.Sprintf("igm-test-%s", acctest.RandString(10))
+	igmName := fmt.Sprintf("igm-test-%s", acctest.RandString(10))
 
 	resource.Test(t, resource.TestCase{
 		PreCheck:     func() { testAccPreCheck(t) },
@@ -51,7 +51,7 @@ func TestAccInstanceGroupManager_targetSizeZero(t *testing.T) {
 		CheckDestroy: testAccCheckInstanceGroupManagerDestroy,
 		Steps: []resource.TestStep{
 			resource.TestStep{
-				Config: testAccInstanceGroupManager_targetSizeZero(template, igm),
+				Config: testAccInstanceGroupManager_targetSizeZero(templateName, igmName),
 				Check: resource.ComposeTestCheckFunc(
 					testAccCheckInstanceGroupManagerExists(
 						"google_compute_instance_group_manager.igm-basic", &manager),
diff --git a/website/docs/r/compute_instance_group_manager.html.markdown b/website/docs/r/compute_instance_group_manager.html.markdown
index d07d9cb8..963bd0e4 100644
--- a/website/docs/r/compute_instance_group_manager.html.markdown
+++ b/website/docs/r/compute_instance_group_manager.html.markdown
@@ -74,9 +74,9 @@ The following arguments are supported:
     restart all of the instances at once. In the future, as the GCE API matures
     we will support `"ROLLING_UPDATE"` as well.
 
-* `target_size` - (Optional, Default `0`) The target number of running instances for this managed
+* `target_size` - (Optional) The target number of running instances for this managed
     instance group. This value should always be explicitly set unless this resource is attached to
-     an autoscaler, in which case it should never be set.
+     an autoscaler, in which case it should never be set. Defaults to `0`.
 
 * `target_pools` - (Optional) The full URL of all target pools to which new
     instances in the group are added. Updating the target pools attribute does