diff --git a/src/plugins/sqldrivers/ibase/qsql_ibase.cpp b/src/plugins/sqldrivers/ibase/qsql_ibase.cpp
index 8f08b023bbb..aad8cead880 100644
--- a/src/plugins/sqldrivers/ibase/qsql_ibase.cpp
+++ b/src/plugins/sqldrivers/ibase/qsql_ibase.cpp
@@ -263,16 +263,20 @@ static inline QDateTime fromTimeStampTz(const char *buffer)
 
     QByteArray timeZoneName = qFbTzIdToIanaIdMap()->value(fpTzID);
     if (!timeZoneName.isEmpty())
-        return QDateTime(d, t, QTimeZone(timeZoneName));
+    {
+        const auto utc = QDateTime(d, t, QTimeZone(QTimeZone::UTC));
+        return utc.toTimeZone(QTimeZone(timeZoneName));
+    }
     else
         return {};
 }
 
 static inline ISC_TIMESTAMP_TZ toTimeStampTz(const QDateTime &dt)
 {
+    const auto dtUtc = dt.toUTC();
     ISC_TIMESTAMP_TZ ts;
-    ts.utc_timestamp.timestamp_time = dt.time().msecsSinceStartOfDay() * 10;
-    ts.utc_timestamp.timestamp_date = s_ibaseBaseDate.daysTo(dt.date());
+    ts.utc_timestamp.timestamp_time = dtUtc.time().msecsSinceStartOfDay() * 10;
+    ts.utc_timestamp.timestamp_date = s_ibaseBaseDate.daysTo(dtUtc.date());
     ts.time_zone = qIanaIdToFbTzIdMap()->value(dt.timeZone().id().simplified(), 0);
     return ts;
 }
diff --git a/tests/auto/sql/kernel/qsqlquery/tst_qsqlquery.cpp b/tests/auto/sql/kernel/qsqlquery/tst_qsqlquery.cpp
index ee34995f8ee..653c898cbc7 100644
--- a/tests/auto/sql/kernel/qsqlquery/tst_qsqlquery.cpp
+++ b/tests/auto/sql/kernel/qsqlquery/tst_qsqlquery.cpp
@@ -259,6 +259,9 @@ private slots:
     void ibaseInt128_data() { generic_data("QIBASE"); }
     void ibaseInt128();
 
+    void QTBUG_128493_data() { generic_data("QIBASE"); }
+    void QTBUG_128493();
+
 
     void psqlJsonOperator_data() { generic_data("QPSQL"); }
     void psqlJsonOperator();
@@ -4868,6 +4871,56 @@ void tst_QSqlQuery::ibaseDateTimeWithTZ()
     }
 }
 
+void tst_QSqlQuery::QTBUG_128493()
+{
+    QFETCH(QString, dbName);
+    QSqlDatabase db = QSqlDatabase::database(dbName);
+    CHECK_DATABASE(db);
+    if (tst_Databases::getDatabaseType(db) != QSqlDriver::Interbase)
+        QSKIP("Implemented only for Interbase");
+
+    if (tst_Databases::getIbaseEngineVersion(db).majorVersion() < 4)
+        QSKIP("Time zone support only implemented for firebird engine version 4 and greater");
+
+
+    QSqlQuery q{db};
+
+#if QT_CONFIG(timezone)
+    const auto currentDateTime = QDateTime::currentDateTime().toTimeZone(QTimeZone("Europe/Vienna"_ba));
+    //Set session time zone
+    QVERIFY_SQL(q, exec(u"set time zone 'Europe/Vienna'"_s));
+#else
+    const auto currentDateTime = QDateTime::currentDateTime();
+#endif // QT_CONFIG(timezone)
+
+    QVERIFY_SQL(q, exec(u"select current_timestamp from rdb$database"_s));
+    QVERIFY_SQL(q, isActive());
+    QVERIFY_SQL(q, next());
+    const auto currentDateTimeDB = q.value(0).toDateTime();
+
+    QCOMPARE(currentDateTime.date(), currentDateTimeDB.date());
+    QCOMPARE(currentDateTime.offsetFromUtc(), currentDateTimeDB.offsetFromUtc());
+    QCOMPARE(currentDateTime.isDaylightTime(), currentDateTimeDB.isDaylightTime());
+
+    QCOMPARE(currentDateTime.time().hour(), currentDateTimeDB.time().hour());
+
+    const QString tableName(qTableName(u"dateTimeTS"_s, __FILE__, db));
+    QVERIFY_SQL(q, exec(u"CREATE TABLE "_s + tableName + u"(dt timestamp with time zone)"_s));
+
+    QVERIFY_SQL(q, prepare(u"INSERT INTO %1 values(:dt)"_s.arg(tableName)));
+    q.bindValue(":dt", currentDateTime );
+    QVERIFY_SQL(q, exec());
+
+    QVERIFY_SQL(q, exec(u"SELECT cast(dt AS VARCHAR(50)) FROM "_s + tableName));
+    QVERIFY_SQL(q, next());
+
+    const auto currentDateTimeFromDBString = q.value(0).toString();
+    auto currentDateTimeFromDB = QDateTime::fromString(currentDateTimeFromDBString,
+                                                       u"yyyy-MM-dd hh:mm:ss.zzz0 tttt"_s);
+
+    QCOMPARE(currentDateTimeFromDB, currentDateTime);
+}
+
 void tst_QSqlQuery::sqliteVirtualTable()
 {
     // Virtual tables can behave differently when it comes to prepared