diff --git a/runtime/runtime_impl_jetty12/src/main/java/com/google/apphosting/runtime/jetty/ee10/ResourceFileServlet.java b/runtime/runtime_impl_jetty12/src/main/java/com/google/apphosting/runtime/jetty/ee10/ResourceFileServlet.java
index 93c4f42d..3f687732 100644
--- a/runtime/runtime_impl_jetty12/src/main/java/com/google/apphosting/runtime/jetty/ee10/ResourceFileServlet.java
+++ b/runtime/runtime_impl_jetty12/src/main/java/com/google/apphosting/runtime/jetty/ee10/ResourceFileServlet.java
@@ -16,8 +16,8 @@
 
 package com.google.apphosting.runtime.jetty.ee10;
 
-import com.google.apphosting.runtime.AppVersion;
 import com.google.apphosting.runtime.AppEngineConstants;
+import com.google.apphosting.runtime.AppVersion;
 import com.google.apphosting.utils.config.AppYaml;
 import com.google.common.base.Ascii;
 import com.google.common.flogger.GoogleLogger;
@@ -27,6 +27,9 @@
 import jakarta.servlet.http.HttpServlet;
 import jakarta.servlet.http.HttpServletRequest;
 import jakarta.servlet.http.HttpServletResponse;
+import java.io.IOException;
+import java.net.URL;
+import java.util.Objects;
 import org.eclipse.jetty.ee10.servlet.ServletContextHandler;
 import org.eclipse.jetty.ee10.servlet.ServletHandler;
 import org.eclipse.jetty.ee10.servlet.ServletMapping;
@@ -36,9 +39,6 @@
 import org.eclipse.jetty.util.resource.Resource;
 import org.eclipse.jetty.util.resource.ResourceFactory;
 
-import java.io.IOException;
-import java.util.Objects;
-
 /**
  * {@code ResourceFileServlet} is a copy of {@code org.mortbay.jetty.servlet.DefaultServlet} that
  * has been trimmed down to only support the subset of features that we want to take advantage of
@@ -88,9 +88,8 @@ public void init() throws ServletException {
     defaultServletName = servletMapping.getServletName();
 
     try {
-      // TODO: review use of root factory.
-      resourceBase =
-          ResourceFactory.root().newResource(context.getResource("/" + appVersion.getPublicRoot()));
+      URL resourceBaseUrl = context.getResource("/" + appVersion.getPublicRoot());
+      resourceBase = (resourceBaseUrl == null) ? null : ResourceFactory.of(chandler).newResource(resourceBaseUrl);
     } catch (Exception ex) {
       throw new ServletException(ex);
     }
diff --git a/runtime/runtime_impl_jetty12/src/main/java/com/google/apphosting/runtime/jetty/ee8/ResourceFileServlet.java b/runtime/runtime_impl_jetty12/src/main/java/com/google/apphosting/runtime/jetty/ee8/ResourceFileServlet.java
index f79c6ded..4b516e8d 100644
--- a/runtime/runtime_impl_jetty12/src/main/java/com/google/apphosting/runtime/jetty/ee8/ResourceFileServlet.java
+++ b/runtime/runtime_impl_jetty12/src/main/java/com/google/apphosting/runtime/jetty/ee8/ResourceFileServlet.java
@@ -16,12 +16,13 @@
 
 package com.google.apphosting.runtime.jetty.ee8;
 
-import com.google.apphosting.runtime.AppVersion;
 import com.google.apphosting.runtime.AppEngineConstants;
+import com.google.apphosting.runtime.AppVersion;
 import com.google.apphosting.utils.config.AppYaml;
 import com.google.common.base.Ascii;
 import com.google.common.flogger.GoogleLogger;
 import java.io.IOException;
+import java.net.URL;
 import java.util.Objects;
 import javax.servlet.RequestDispatcher;
 import javax.servlet.ServletContext;
@@ -79,8 +80,8 @@ public void init() throws ServletException {
     welcomeFiles = chandler.getWelcomeFiles();
 
     try {
-      // TODO: review use of root factory.
-      resourceBase = ResourceFactory.root().newResource(context.getResource("/" + appVersion.getPublicRoot()));
+      URL resourceBaseUrl = context.getResource("/" + appVersion.getPublicRoot());
+      resourceBase = (resourceBaseUrl == null) ? null : ResourceFactory.of(chandler).newResource(resourceBaseUrl);
     } catch (Exception ex) {
       throw new ServletException(ex);
     }