diff --git a/builder/googlecompute/config_test.go b/builder/googlecompute/config_test.go
index 438a1bd06..d7dd11ebc 100644
--- a/builder/googlecompute/config_test.go
+++ b/builder/googlecompute/config_test.go
@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"io/ioutil"
 	"os"
+	"runtime"
 	"strings"
 	"testing"
 )
@@ -401,8 +402,14 @@ func TestConfigPrepareIAP(t *testing.T) {
 	if c.IAPHashBang != "/bin/sh" {
 		t.Fatalf("IAP hashbang didn't default correctly to /bin/sh.")
 	}
-	if c.IAPExt != ".sh" {
-		t.Fatalf("IAP tempfile extension didn't default correctly to .sh")
+	if runtime.GOOS == "windows" {
+		if c.IAPExt != ".cmd" {
+			t.Fatalf("IAP tempfile extension didn't default correctly to .cmd")
+		}
+	} else {
+		if c.IAPExt != "" {
+			t.Fatalf("IAP tempfile extension should default to empty on unix mahcines")
+		}
 	}
 	if c.Comm.SSHHost != "localhost" {
 		t.Fatalf("Didn't correctly override the ssh host.")
diff --git a/builder/googlecompute/step_start_tunnel_test.go b/builder/googlecompute/step_start_tunnel_test.go
index 48634008d..cf8a8b56f 100644
--- a/builder/googlecompute/step_start_tunnel_test.go
+++ b/builder/googlecompute/step_start_tunnel_test.go
@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"io/ioutil"
 	"os"
+	"runtime"
 	"testing"
 
 	"github.com/hashicorp/packer/helper/communicator"
@@ -38,6 +39,7 @@ func getTestStepStartTunnel() *StepStartTunnel {
 			},
 		},
 		AccountFile: "/path/to/account_file.json",
+		ProjectId:   "fake-project-123",
 	}
 }
 
@@ -57,10 +59,20 @@ func TestStepStartTunnel_CreateTempScript(t *testing.T) {
 	if err != nil {
 		t.Fatalf("couldn't read created inventoryfile: %s", err)
 	}
+
 	expected := `#!/bin/bash
+
 gcloud auth activate-service-account --key-file='/path/to/account_file.json'
+gcloud config set project fake-project-123
 gcloud compute start-iap-tunnel fakeinstance-12345 1234 --local-host-port=localhost:8774 --zone us-central-b
 `
+	if runtime.GOOS == "windows" {
+		expected = `
+call gcloud auth activate-service-account --key-file /path/to/account_file.json
+call gcloud config set project fake-project-123
+call gcloud compute start-iap-tunnel fakeinstance-12345 1234 --local-host-port=localhost:8774 --zone us-central-b
+`
+	}
 	if fmt.Sprintf("%s", f) != expected {
 		t.Fatalf("script didn't match expected:\n\n expected: \n%s\n; recieved: \n%s\n", expected, f)
 	}