diff --git a/go/jsbundler/hmr_browser_test.go b/go/jsbundler/hmr_browser_test.go
index f136efed..142970ec 100644
--- a/go/jsbundler/hmr_browser_test.go
+++ b/go/jsbundler/hmr_browser_test.go
@@ -82,7 +82,7 @@ setTimeout(() => {
 }, 0);
 `)
 
-	eps, err := loadVendorManifest(filepath.Join(frontendAbs, "vendor"))
+	eps, err := loadVendorManifest([]string{filepath.Join(frontendAbs, "vendor")})
 	if err != nil {
 		t.Fatalf("vendor manifest: %v", err)
 	}
@@ -90,7 +90,7 @@ setTimeout(() => {
 		hub:               newHub(),
 		frontend:          frontendAbs,
 		srcRoot:           tmpSrc,
-		vendor:            filepath.Join(frontendAbs, "vendor"),
+		vendorDirs:        []string{filepath.Join(frontendAbs, "vendor")},
 		graph:             newModuleGraph(),
 		vendorCache:       map[string][]byte{},
 		cssTrigger:        make(chan struct{}, 1),
diff --git a/go/jsbundler/hmr_e2e_test.go b/go/jsbundler/hmr_e2e_test.go
index 1055e441..99bf1919 100644
--- a/go/jsbundler/hmr_e2e_test.go
+++ b/go/jsbundler/hmr_e2e_test.go
@@ -27,9 +27,9 @@ func TestDevServerAssetURL(t *testing.T) {
 		[]byte(`import u from "pdfjs-dist/build/pdf.worker.min.mjs?url";
 export const url = u;`), 0o644)
 
-	eps, _ := loadVendorManifest(filepath.Join(frontendAbs, "vendor"))
+	eps, _ := loadVendorManifest([]string{filepath.Join(frontendAbs, "vendor")})
 	d := &devServer{hub: newHub(), frontend: frontendAbs, srcRoot: tmpSrc,
-		vendor: filepath.Join(frontendAbs, "vendor"), graph: newModuleGraph(),
+		vendorDirs: []string{filepath.Join(frontendAbs, "vendor")}, graph: newModuleGraph(),
 		vendorCache: map[string][]byte{}, cssTrigger: make(chan struct{}, 1), vendorEntrypoints: eps}
 
 	out, err := d.transformModule(filepath.Join(tmpSrc, "uses-worker.tsx"))
diff --git a/go/jsbundler/hmr_error_test.go b/go/jsbundler/hmr_error_test.go
index 44e35a55..1d3b68c2 100644
--- a/go/jsbundler/hmr_error_test.go
+++ b/go/jsbundler/hmr_error_test.go
@@ -57,9 +57,9 @@ func TestServeModuleCompileErrorServesOverlay(t *testing.T) {
 	os.WriteFile(filepath.Join(tmpSrc, "Broken.tsx"),
 		[]byte("export default function Broken() {\n  return <div><span></div>;\n}\n"), 0o644)
 
-	eps, _ := loadVendorManifest(filepath.Join(frontendAbs, "vendor"))
+	eps, _ := loadVendorManifest([]string{filepath.Join(frontendAbs, "vendor")})
 	d := &devServer{hub: newHub(), frontend: frontendAbs, srcRoot: tmpSrc,
-		vendor: filepath.Join(frontendAbs, "vendor"), graph: newModuleGraph(),
+		vendorDirs: []string{filepath.Join(frontendAbs, "vendor")}, graph: newModuleGraph(),
 		vendorCache: map[string][]byte{}, cssTrigger: make(chan struct{}, 1), vendorEntrypoints: eps}
 
 	req := httptest.NewRequest("GET", srcURLPrefix+"Broken.tsx", nil)