diff --git a/src/corelib/time/qdatetime.cpp b/src/corelib/time/qdatetime.cpp
index c3e9b49b25e..504ededb56f 100644
--- a/src/corelib/time/qdatetime.cpp
+++ b/src/corelib/time/qdatetime.cpp
@@ -2824,11 +2824,13 @@ QDateTimePrivate::ZoneState QDateTimePrivate::expressUtcAsLocal(qint64 utcMSecs)
 #if QT_CONFIG(timezone) // Use the system time-zone.
     if (const auto sys = QTimeZone::systemTimeZone(); sys.isValid()) {
         result.offset = sys.d->offsetFromUtc(utcMSecs);
-        if (qAddOverflow(utcMSecs, result.offset * MSECS_PER_SEC, &result.when))
+        if (result.offset != QTimeZonePrivate::invalidSeconds()) {
+            if (qAddOverflow(utcMSecs, result.offset * MSECS_PER_SEC, &result.when))
+                return result;
+            result.dst = sys.d->isDaylightTime(utcMSecs) ? DaylightTime : StandardTime;
+            result.valid = true;
             return result;
-        result.dst = sys.d->isDaylightTime(utcMSecs) ? DaylightTime : StandardTime;
-        result.valid = true;
-        return result;
+        }
     }
 #endif // timezone
 
diff --git a/src/corelib/time/qtimezoneprivate.cpp b/src/corelib/time/qtimezoneprivate.cpp
index d06c1aa6625..17b32ec2e8e 100644
--- a/src/corelib/time/qtimezoneprivate.cpp
+++ b/src/corelib/time/qtimezoneprivate.cpp
@@ -341,6 +341,12 @@ QDateTimePrivate::ZoneState QTimeZonePrivate::stateAtZoneTime(
     Q_ASSERT(recent < imminent && seventeenHoursInMSecs < imminent - recent + 1);
 
     const Data past = data(recent), future = data(imminent);
+    if (future.atMSecsSinceEpoch == invalidMSecs()
+        && past.atMSecsSinceEpoch == invalidMSecs()) {
+        // Failed to get any useful data near this time: apparently out of range
+        // for the backend.
+        return { forLocalMSecs };
+    }
     // > 99% of the time, past and future will agree:
     if (Q_LIKELY(past.offsetFromUtc == future.offsetFromUtc
                  && past.standardTimeOffset == future.standardTimeOffset