diff --git a/src/main/java/org/apache/commons/lang3/time/StopWatch.java b/src/main/java/org/apache/commons/lang3/time/StopWatch.java
index 1046844df2e..1564c5442bf 100644
--- a/src/main/java/org/apache/commons/lang3/time/StopWatch.java
+++ b/src/main/java/org/apache/commons/lang3/time/StopWatch.java
@@ -327,7 +327,7 @@ public StopWatch(final String message) {
      * @since 3.10
      */
     public String formatSplitTime() {
-        return DurationFormatUtils.formatDurationHMS(DurationUtils.toMillisInt(getSplitDuration()));
+        return DurationFormatUtils.formatDurationHMS(DurationUtils.toMillisLong(getSplitDuration()));
     }
 
     /**
diff --git a/src/test/java/org/apache/commons/lang3/time/StopWatchTest.java b/src/test/java/org/apache/commons/lang3/time/StopWatchTest.java
index d42b790322b..03458972ce7 100644
--- a/src/test/java/org/apache/commons/lang3/time/StopWatchTest.java
+++ b/src/test/java/org/apache/commons/lang3/time/StopWatchTest.java
@@ -147,6 +147,17 @@ void testFormatSplitTime() {
         assertTrue(formatSplitTime.startsWith(ZERO_HOURS_PREFIX), "formatSplitTime");
     }
 
+    @Test
+    void testFormatSplitTimeExceedingIntMillis() throws Exception {
+        final StopWatch watch = StopWatch.createStarted();
+        // Backdate the start so the split spans more than Integer.MAX_VALUE milliseconds (about 24.86 days).
+        FieldUtils.writeField(watch, "startTimeNanos", System.nanoTime() - TimeUnit.DAYS.toNanos(30), true);
+        watch.split();
+        final long splitMillis = watch.getSplitDuration().toMillis();
+        assertTrue(splitMillis > Integer.MAX_VALUE, "precondition: split must exceed Integer.MAX_VALUE millis");
+        assertEquals(DurationFormatUtils.formatDurationHMS(splitMillis), watch.formatSplitTime(), "formatSplitTime");
+    }
+
     @Test
     void testFormatSplitTimeWithMessage() {
         final StopWatch watch = new StopWatch(MESSAGE);