diff --git a/src/corelib/text/qlocale.cpp b/src/corelib/text/qlocale.cpp
index 684365f3406..6d96ca70d9d 100644
--- a/src/corelib/text/qlocale.cpp
+++ b/src/corelib/text/qlocale.cpp
@@ -5036,8 +5036,10 @@ QStringList QLocale::uiLanguages(TagSeparator separator) const
         const auto prior = QString::fromLatin1(id.name(sep));
         if (isSystem && i < uiLanguages.size()) {
             // Adding likely-adjusted forms to system locale's list.
+            Q_ASSERT(uiLanguages.at(i) == prior
+                     // A legacy code may get mapped to an ID with a different name:
+                     || QLatin1String(QLocaleId::fromName(uiLanguages.at(i)).name(sep)) == prior);
             // Insert just after the entry we're supplementing:
-            Q_ASSERT(uiLanguages.at(i) == prior);
             j = i + 1;
         } else {
             // Plain locale or empty system uiLanguages; just append.
diff --git a/tests/auto/corelib/text/qlocale/tst_qlocale.cpp b/tests/auto/corelib/text/qlocale/tst_qlocale.cpp
index 6ec8fa9aecd..a842841949f 100644
--- a/tests/auto/corelib/text/qlocale/tst_qlocale.cpp
+++ b/tests/auto/corelib/text/qlocale/tst_qlocale.cpp
@@ -4090,6 +4090,10 @@ public:
                 return QVariant(QStringList{u"en-CA"_s, u"fr-CA"_s, u"de-AT"_s,
                                             u"en-GB"_s, u"fr-FR"_s});
             }
+            if (m_name == u"no") // QTBUG-131127
+                return QVariant(QStringList{u"no"_s, u"en-US"_s, u"nb"_s});
+            if (m_name == u"no-US") // Empty query result:
+                return QVariant(QStringList{});
             return QVariant(QStringList{m_name});
         case LanguageId:
             return m_id.language_id;
@@ -4122,6 +4126,15 @@ void tst_QLocale::mySystemLocale_data()
     QTest::addColumn<QLocale::Language>("language");
     QTest::addColumn<QStringList>("uiLanguages");
 
+    QTest::addRow("empty")
+        << u"no-US"_s << QLocale::NorwegianBokmal
+        << QStringList{u"nb-US"_s, u"nb-Latn-US"_s,
+                       u"nb-Latn-NO"_s, u"nb-NO"_s, u"nb"_s, u"nb-Latn"_s};
+    QTest::addRow("no") // QTBUG-131127
+        << u"no"_s << QLocale::NorwegianBokmal
+        << QStringList{u"no"_s, u"nb-Latn-NO"_s, u"nb-NO"_s, u"en-US"_s, u"en-Latn-US"_s, u"en"_s,
+                       u"nb"_s, u"nb-Latn-NO"_s, u"nb-NO"_s, u"nb-Latn"_s, u"en-Latn"_s};
+
     QTest::addRow("catalan")
         << u"ca"_s << QLocale::Catalan
         << QStringList{u"ca"_s, u"ca-Latn-ES"_s, u"ca-ES"_s, u"ca-Latn"_s};