diff --git a/jib-core/src/test/java/com/google/cloud/tools/jib/http/TestWebServer.java b/jib-core/src/test/java/com/google/cloud/tools/jib/http/TestWebServer.java
index 3633b33302..8fee967e83 100644
--- a/jib-core/src/test/java/com/google/cloud/tools/jib/http/TestWebServer.java
+++ b/jib-core/src/test/java/com/google/cloud/tools/jib/http/TestWebServer.java
@@ -31,6 +31,8 @@
 import java.nio.file.Paths;
 import java.security.GeneralSecurityException;
 import java.security.KeyStore;
+import java.util.Arrays;
+import java.util.List;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
 import java.util.concurrent.Future;
@@ -47,14 +49,26 @@ public class TestWebServer implements Closeable {
   private final Semaphore threadStarted = new Semaphore(0);
   private final StringBuilder inputRead = new StringBuilder();
 
+  private final List<String> responses;
+
   public TestWebServer(boolean https)
       throws IOException, InterruptedException, GeneralSecurityException, URISyntaxException {
+    this(https, Arrays.asList("HTTP/1.1 200 OK\nContent-Length:12\n\nHello World!"));
+  }
+
+  public TestWebServer(boolean https, List<String> responses)
+      throws IOException, InterruptedException, GeneralSecurityException, URISyntaxException {
     this.https = https;
-    serverSocket = createServerSocket(https);
-    ignoreReturn(executorService.submit(this::serve200));
+    this.responses = responses;
+    serverSocket = https ? createHttpsServerSocket() : new ServerSocket(0);
+    ignoreReturn(executorService.submit(this::serveResponses));
     threadStarted.acquire();
   }
 
+  public int getLocalPort() {
+    return serverSocket.getLocalPort();
+  }
+
   public String getEndpoint() {
     String host = serverSocket.getInetAddress().getHostAddress();
     return (https ? "https" : "http") + "://" + host + ":" + serverSocket.getLocalPort();
@@ -66,47 +80,45 @@ public void close() throws IOException {
     executorService.shutdown();
   }
 
-  private ServerSocket createServerSocket(boolean https)
+  private ServerSocket createHttpsServerSocket()
       throws IOException, GeneralSecurityException, URISyntaxException {
-    if (https) {
-      KeyStore keyStore = KeyStore.getInstance("JKS");
-      // generated with: keytool -genkey -keyalg RSA -keystore ./TestWebServer-keystore
-      Path keyStoreFile = Paths.get(Resources.getResource("core/TestWebServer-keystore").toURI());
-      try (InputStream in = Files.newInputStream(keyStoreFile)) {
-        keyStore.load(in, "password".toCharArray());
-      }
+    KeyStore keyStore = KeyStore.getInstance("JKS");
+    // generated with: keytool -genkey -keyalg RSA -keystore ./TestWebServer-keystore
+    Path keyStoreFile = Paths.get(Resources.getResource("core/TestWebServer-keystore").toURI());
+    try (InputStream in = Files.newInputStream(keyStoreFile)) {
+      keyStore.load(in, "password".toCharArray());
+    }
 
-      KeyManagerFactory keyManagerFactory =
-          KeyManagerFactory.getInstance(KeyManagerFactory.getDefaultAlgorithm());
-      keyManagerFactory.init(keyStore, "password".toCharArray());
+    KeyManagerFactory keyManagerFactory =
+        KeyManagerFactory.getInstance(KeyManagerFactory.getDefaultAlgorithm());
+    keyManagerFactory.init(keyStore, "password".toCharArray());
 
-      SSLContext sslContext = SSLContext.getInstance("TLS");
-      sslContext.init(keyManagerFactory.getKeyManagers(), null, null);
-      return sslContext.getServerSocketFactory().createServerSocket(0);
-    } else {
-      return new ServerSocket(0);
-    }
+    SSLContext sslContext = SSLContext.getInstance("TLS");
+    sslContext.init(keyManagerFactory.getKeyManagers(), null, null);
+    return sslContext.getServerSocketFactory().createServerSocket(0);
   }
 
-  private Void serve200() throws IOException {
+  private Void serveResponses() throws IOException {
     threadStarted.release();
     try (Socket socket = serverSocket.accept()) {
-
       InputStream in = socket.getInputStream();
       BufferedReader reader = new BufferedReader(new InputStreamReader(in, StandardCharsets.UTF_8));
-      for (String line = reader.readLine();
-          line != null && !line.isEmpty(); // An empty line marks the end of an HTTP request.
-          line = reader.readLine()) {
-        inputRead.append(line + "\n");
-      }
 
-      String response = "HTTP/1.1 200 OK\nContent-Length:12\n\nHello World!";
-      socket.getOutputStream().write(response.getBytes(StandardCharsets.UTF_8));
-      socket.getOutputStream().flush();
+      for (String response : responses) {
+        for (String line = reader.readLine();
+            line != null && !line.isEmpty(); // An empty line marks the end of an HTTP request.
+            line = reader.readLine()) {
+          inputRead.append(line + "\n");
+        }
+        socket.getOutputStream().write(response.getBytes(StandardCharsets.UTF_8));
+        socket.getOutputStream().flush();
+      }
     }
     return null;
   }
 
+  // For use to ignore (i.e., accept and do nothing) a return value from ExecutionService.submit().
+  // Without "consuming" the return value this way, Error Prone will complain to use it.
   private void ignoreReturn(Future<Void> future) {
     // do nothing; to make Error Prone happy
   }
diff --git a/jib-core/src/test/java/com/google/cloud/tools/jib/http/WithServerConnectionTest.java b/jib-core/src/test/java/com/google/cloud/tools/jib/http/WithServerConnectionTest.java
index 52dd89eb78..678b92ff53 100644
--- a/jib-core/src/test/java/com/google/cloud/tools/jib/http/WithServerConnectionTest.java
+++ b/jib-core/src/test/java/com/google/cloud/tools/jib/http/WithServerConnectionTest.java
@@ -22,7 +22,9 @@
 import java.net.URL;
 import java.nio.charset.StandardCharsets;
 import java.security.GeneralSecurityException;
+import java.util.Arrays;
 import javax.net.ssl.SSLException;
+import org.hamcrest.CoreMatchers;
 import org.junit.Assert;
 import org.junit.Test;
 
@@ -89,4 +91,36 @@ public void testInsecureConnection()
           ByteStreams.toByteArray(response.getBody()));
     }
   }
+
+  @Test
+  public void testProxyCredentialProperties()
+      throws IOException, InterruptedException, GeneralSecurityException, URISyntaxException {
+    String proxyResponse =
+        "HTTP/1.1 407 Proxy Authentication Required\n"
+            + "Proxy-Authenticate: BASIC realm=\"some-realm\"\n"
+            + "Cache-Control: no-cache\n"
+            + "Pragma: no-cache\n"
+            + "Content-Length: 0\n\n";
+    String targetServerResponse = "HTTP/1.1 200 OK\nContent-Length:12\n\nHello World!";
+
+    try (TestWebServer server =
+        new TestWebServer(false, Arrays.asList(proxyResponse, targetServerResponse))) {
+      System.setProperty("http.proxyHost", "localhost");
+      System.setProperty("http.proxyPort", String.valueOf(server.getLocalPort()));
+      System.setProperty("http.proxyUser", "user_sys_prop");
+      System.setProperty("http.proxyPassword", "pass_sys_prop");
+
+      try (Connection connection =
+          Connection.getConnectionFactory().apply(new URL("http://does.not.matter"))) {
+        Response response = connection.send("GET", new Request.Builder().build());
+        Assert.assertThat(
+            server.getInputRead(),
+            CoreMatchers.containsString(
+                "Proxy-Authorization: Basic dXNlcl9zeXNfcHJvcDpwYXNzX3N5c19wcm9w"));
+        Assert.assertArrayEquals(
+            "Hello World!".getBytes(StandardCharsets.UTF_8),
+            ByteStreams.toByteArray(response.getBody()));
+      }
+    }
+  }
 }