diff --git a/core/src/main/java/hudson/Functions.java b/core/src/main/java/hudson/Functions.java
index 6ebe09dd88..2e6abc9785 100644
--- a/core/src/main/java/hudson/Functions.java
+++ b/core/src/main/java/hudson/Functions.java
@@ -221,12 +221,12 @@ public class Functions {
     }
 
     public static String xsDate(Calendar cal) {
-        return Util.XS_DATETIME_FORMATTER.format(cal.getTime());
+        return Util.XS_DATETIME_FORMATTER2.format(cal.toInstant());
     }
 
     @Restricted(NoExternalUse.class)
     public static String iso8601DateTime(Date date) {
-        return Util.XS_DATETIME_FORMATTER.format(date);
+        return Util.XS_DATETIME_FORMATTER2.format(date.toInstant());
     }
 
     /**
diff --git a/core/src/main/java/hudson/Util.java b/core/src/main/java/hudson/Util.java
index 340a717067..abe9f97d65 100644
--- a/core/src/main/java/hudson/Util.java
+++ b/core/src/main/java/hudson/Util.java
@@ -84,6 +84,7 @@ import java.text.NumberFormat;
 import java.text.ParseException;
 import java.time.LocalDate;
 import java.time.ZoneId;
+import java.time.ZoneOffset;
 import java.time.format.DateTimeFormatter;
 import java.time.temporal.ChronoUnit;
 import java.util.ArrayList;
@@ -1873,8 +1874,15 @@ public class Util {
                 "<!--%n", Functions.htmlAttributeEscape(redirectUrl), message);
     }
 
+    /**
+     * @deprecated use {@link #XS_DATETIME_FORMATTER2}
+     */
+    @Deprecated
     public static final FastDateFormat XS_DATETIME_FORMATTER = FastDateFormat.getInstance("yyyy-MM-dd'T'HH:mm:ss'Z'", new SimpleTimeZone(0, "GMT"));
 
+    public static final DateTimeFormatter XS_DATETIME_FORMATTER2 =
+            DateTimeFormatter.ofPattern("yyyy-MM-dd'T'HH:mm:ss'Z'").withZone(ZoneOffset.UTC);
+
     // Note: RFC822 dates must not be localized!
     /**
      * @deprecated use {@link DateTimeFormatter#RFC_1123_DATE_TIME}
diff --git a/core/src/main/java/hudson/model/Run.java b/core/src/main/java/hudson/model/Run.java
index 4ea3a0c5bc..a2061b162b 100644
--- a/core/src/main/java/hudson/model/Run.java
+++ b/core/src/main/java/hudson/model/Run.java
@@ -87,6 +87,7 @@ import java.nio.file.StandardCopyOption;
 import java.nio.file.StandardOpenOption;
 import java.text.DateFormat;
 import java.text.SimpleDateFormat;
+import java.time.Instant;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Calendar;
@@ -766,7 +767,7 @@ public abstract class Run<JobT extends Job<JobT, RunT>, RunT extends Run<JobT, R
      * Returns the timestamp formatted in xs:dateTime.
      */
     public @NonNull String getTimestampString2() {
-        return Util.XS_DATETIME_FORMATTER.format(new Date(timestamp));
+        return Util.XS_DATETIME_FORMATTER2.format(Instant.ofEpochMilli(timestamp));
     }
 
     /**
diff --git a/core/src/main/java/jenkins/widgets/BuildListTable.java b/core/src/main/java/jenkins/widgets/BuildListTable.java
index 495d7e50be..aa5da494de 100644
--- a/core/src/main/java/jenkins/widgets/BuildListTable.java
+++ b/core/src/main/java/jenkins/widgets/BuildListTable.java
@@ -28,7 +28,7 @@ import hudson.Functions;
 import hudson.Util;
 import hudson.model.BallColor;
 import hudson.model.Run;
-import java.util.Date;
+import java.time.Instant;
 import jenkins.console.ConsoleUrlProvider;
 import net.sf.json.JSONObject;
 import org.kohsuke.accmod.Restricted;
@@ -49,7 +49,7 @@ public class BuildListTable extends RunListProgressiveRendering {
         element.put("displayName", build.getDisplayName());
         element.put("timestampString", build.getTimestampString());
         element.put("timestampString2", build.getTimestampString2());
-        element.put("timestampString3", Util.XS_DATETIME_FORMATTER.format(new Date(build.getStartTimeInMillis())));
+        element.put("timestampString3", Util.XS_DATETIME_FORMATTER2.format(Instant.ofEpochMilli(build.getStartTimeInMillis())));
         Run.Summary buildStatusSummary = build.getBuildStatusSummary();
         element.put("buildStatusSummaryWorse", buildStatusSummary.isWorse);
         element.put("buildStatusSummaryMessage", buildStatusSummary.message);