diff --git a/builder/googlecompute/config_test.go b/builder/googlecompute/config_test.go
index 2b450ed9b..5c6ea6334 100644
--- a/builder/googlecompute/config_test.go
+++ b/builder/googlecompute/config_test.go
@@ -168,6 +168,13 @@ func TestImageName(t *testing.T) {
 	}
 }
 
+func TestRegion(t *testing.T) {
+	c, _, _ := NewConfig(testConfig(t))
+	if c.Region != "us-east1" {
+		t.Fatalf("Region should be 'us-east1' given Zone of 'us-east1-a', but is %s", c.Region)
+	}
+}
+
 // Helper stuff below
 
 func testConfig(t *testing.T) map[string]interface{} {
@@ -175,7 +182,7 @@ func testConfig(t *testing.T) map[string]interface{} {
 		"account_file": testAccountFile(t),
 		"project_id":   "hashicorp",
 		"source_image": "foo",
-		"zone":         "us-east-1a",
+		"zone":         "us-east1-a",
 	}
 }
 
diff --git a/website/source/docs/builders/googlecompute.html.markdown b/website/source/docs/builders/googlecompute.html.markdown
index cebb1d484..1e7efde26 100644
--- a/website/source/docs/builders/googlecompute.html.markdown
+++ b/website/source/docs/builders/googlecompute.html.markdown
@@ -142,6 +142,10 @@ builder.
 -   `state_timeout` (string) - The time to wait for instance state changes.
     Defaults to `"5m"`.
 
+-   `subnetwork` (string) - The Google Compute subnetwork to use for the launced
+     instance. Only required if the `network` has been created with custom
+     subnetting.
+
 -   `tags` (array of strings)
 
 -   `use_internal_ip` (boolean) - If true, use the instance's internal IP