diff --git a/manager_test.go b/manager_test.go
index 752bef2..1f7539b 100644
--- a/manager_test.go
+++ b/manager_test.go
@@ -62,7 +62,7 @@ func mkNaiveSM(t *testing.T) (*SourceMgr, func()) {
 
 func init() {
 	_, filename, _, _ := runtime.Caller(1)
-	bd = path.Dir(filename)
+	bd = filepath.Dir(filename)
 }
 
 func TestSourceManagerInit(t *testing.T) {
@@ -83,7 +83,7 @@ func TestSourceManagerInit(t *testing.T) {
 		t.Errorf("Should have gotten CouldNotCreateLockError error type, but got %T", te)
 	}
 
-	if _, err = os.Stat(path.Join(cpath, "sm.lock")); err != nil {
+	if _, err = os.Stat(filepath.Join(cpath, "sm.lock")); err != nil {
 		t.Errorf("Global cache lock file not created correctly")
 	}
 
@@ -93,7 +93,7 @@ func TestSourceManagerInit(t *testing.T) {
 		t.Errorf("removeAll failed: %s", err)
 	}
 
-	if _, err = os.Stat(path.Join(cpath, "sm.lock")); !os.IsNotExist(err) {
+	if _, err = os.Stat(filepath.Join(cpath, "sm.lock")); !os.IsNotExist(err) {
 		t.Errorf("Global cache lock file not cleared correctly on Release()")
 		t.FailNow()
 	}
diff --git a/result.go b/result.go
index e38f08d..0bbdf09 100644
--- a/result.go
+++ b/result.go
@@ -3,7 +3,6 @@ package gps
 import (
 	"fmt"
 	"os"
-	"path"
 	"path/filepath"
 )
 
@@ -46,7 +45,7 @@ func WriteDepTree(basedir string, l Lock, sm SourceManager, sv bool) error {
 
 	// TODO(sdboyer) parallelize
 	for _, p := range l.Projects() {
-		to := path.Join(basedir, string(p.Ident().ProjectRoot))
+		to := filepath.Join(basedir, string(p.Ident().ProjectRoot))
 
 		err := os.MkdirAll(to, 0777)
 		if err != nil {
diff --git a/result_test.go b/result_test.go
index d0fd972..09af5a2 100644
--- a/result_test.go
+++ b/result_test.go
@@ -2,7 +2,7 @@ package gps
 
 import (
 	"os"
-	"path"
+	"path/filepath"
 	"testing"
 )
 
@@ -45,19 +45,19 @@ func TestWriteDepTree(t *testing.T) {
 
 	r := basicResult
 
-	tmp := path.Join(os.TempDir(), "vsolvtest")
+	tmp := filepath.Join(os.TempDir(), "vsolvtest")
 	os.RemoveAll(tmp)
 
 	sm, clean := mkNaiveSM(t)
 	defer clean()
 
 	// nil lock/result should err immediately
-	err := WriteDepTree(path.Join(tmp, "export"), nil, sm, true)
+	err := WriteDepTree(filepath.Join(tmp, "export"), nil, sm, true)
 	if err == nil {
 		t.Errorf("Should error if nil lock is passed to WriteDepTree")
 	}
 
-	err = WriteDepTree(path.Join(tmp, "export"), r, sm, true)
+	err = WriteDepTree(filepath.Join(tmp, "export"), r, sm, true)
 	if err != nil {
 		t.Errorf("Unexpected error while creating vendor tree: %s", err)
 	}
@@ -70,10 +70,10 @@ func BenchmarkCreateVendorTree(b *testing.B) {
 	b.SetParallelism(1)
 
 	r := basicResult
-	tmp := path.Join(os.TempDir(), "vsolvtest")
+	tmp := filepath.Join(os.TempDir(), "vsolvtest")
 
 	clean := true
-	sm, err := NewSourceManager(naiveAnalyzer{}, path.Join(tmp, "cache"))
+	sm, err := NewSourceManager(naiveAnalyzer{}, filepath.Join(tmp, "cache"))
 	if err != nil {
 		b.Errorf("NewSourceManager errored unexpectedly: %q", err)
 		clean = false
@@ -91,7 +91,7 @@ func BenchmarkCreateVendorTree(b *testing.B) {
 	if clean {
 		b.ResetTimer()
 		b.StopTimer()
-		exp := path.Join(tmp, "export")
+		exp := filepath.Join(tmp, "export")
 		for i := 0; i < b.N; i++ {
 			// Order the loop this way to make it easy to disable final cleanup, to
 			// ease manual inspection
diff --git a/util.go b/util.go
index 45d3dff..c549ad9 100644
--- a/util.go
+++ b/util.go
@@ -19,6 +19,14 @@ func renameWithFallback(src, dest string) error {
 		return err
 	}
 
+	// Windows cannot use syscall.Rename to rename a directory
+	if runtime.GOOS == "windows" && fi.IsDir() {
+		if err := copyDir(src, dest); err != nil {
+			return err
+		}
+		return os.RemoveAll(src)
+	}
+
 	err = os.Rename(src, dest)
 	if err == nil {
 		return nil
@@ -48,11 +56,7 @@ func renameWithFallback(src, dest string) error {
 		// 0x11 (ERROR_NOT_SAME_DEVICE) is the windows error.
 		// See https://msdn.microsoft.com/en-us/library/cc231199.aspx
 		if ok && noerr == 0x11 {
-			if fi.IsDir() {
-				cerr = copyDir(src, dest)
-			} else {
-				cerr = copyFile(src, dest)
-			}
+			cerr = copyFile(src, dest)
 		}
 	} else {
 		return terr