diff --git a/src/corelib/time/qdatetime.cpp b/src/corelib/time/qdatetime.cpp
index 89aba9a53de..23c9ddedb25 100644
--- a/src/corelib/time/qdatetime.cpp
+++ b/src/corelib/time/qdatetime.cpp
@@ -5883,7 +5883,11 @@ QDateTime QDateTime::fromString(QStringView string, Qt::DateFormat format)
     two digits.
 
     Incorrectly specified fields of the \a string will cause an invalid
-    QDateTime to be returned.
+    QDateTime to be returned. Only datetimes between the local time start of
+    year 100 and end of year 9999 are supported. Note that datetimes near the
+    ends of this range in other time-zones, notably including UTC, may fall
+    outside the range (and thust be treated as invalid) depending on local time
+    zone.
 
     \note Day and month names as well as AM/PM indicators must be given in
     English (C locale).  If localized month and day names or localized forms of
diff --git a/tests/auto/corelib/time/qdatetime/tst_qdatetime.cpp b/tests/auto/corelib/time/qdatetime/tst_qdatetime.cpp
index bad8837ed24..6975a4d9ced 100644
--- a/tests/auto/corelib/time/qdatetime/tst_qdatetime.cpp
+++ b/tests/auto/corelib/time/qdatetime/tst_qdatetime.cpp
@@ -3334,6 +3334,17 @@ void tst_QDateTime::fromStringStringFormat_data()
     QTest::newRow("ASN.1:UTC-end")
             << u"491231235959Z"_s << u"yyMMddHHmmsst"_s << 1950
             << QDate(2049, 12, 31).endOfDay(QTimeZone::UTC).addMSecs(-999);
+    // Reproducer for QTBUG-129287
+    QTest::newRow("ASN.1:max")
+            << u"99991231235959Z"_s << u"yyyyMMddHHmmsst"_s << 1950
+            << QDate(9999, 12, 31).endOfDay(QTimeZone::UTC).addMSecs(-999);
+    // Can also be reproduced with more legible formats:
+    QTest::newRow("UTC:max")
+            << u"9999 Dec 31 23:59:59 +00:00"_s << u"yyyy MMM dd HH:mm:ss t"_s << 9900
+            << QDate(9999, 12, 31).endOfDay(QTimeZone::UTC).addMSecs(-999);
+    QTest::newRow("UTC:min")
+            << u"0100 Jan 1 00:00:00 +00:00"_s << u"yyyy MMM d HH:mm:ss t"_s << 100
+            << QDate(100, 1, 1).startOfDay(QTimeZone::UTC);
 
     // fuzzer test
     QTest::newRow("integer overflow found by fuzzer")
@@ -3359,9 +3370,17 @@ void tst_QDateTime::fromStringStringFormat()
     QFETCH(int, baseYear);
     QFETCH(QDateTime, expected);
 
-    QDateTime dt = QDateTime::fromString(string, format, baseYear);
+    if (futureTimeType == LocalTimeAheadOfUtc) {
+        // The new parser should remove the bounds, removing this limitation.
+        QEXPECT_FAIL("ASN.1:max", "QTBUG-77948: min/max are local times", Abort);
+        QEXPECT_FAIL("UTC:max", "QTBUG-77948: min/max are local times", Abort);
+    }
+    // For contrast, UTC::min gets away with it, which probably means there are
+    // genuinely out-of-range cases the old parser gets wrong.
 
+    QDateTime dt = QDateTime::fromString(string, format, baseYear);
     QCOMPARE(dt, expected);
+
     if (expected.isValid()) {
         QCOMPARE(dt.timeSpec(), expected.timeSpec());
         QCOMPARE(dt.timeRepresentation(), dt.timeRepresentation());