diff --git a/src/common/translation.cpp b/src/common/translation.cpp
index d731165af0..0d58caf3a5 100644
--- a/src/common/translation.cpp
+++ b/src/common/translation.cpp
@@ -1346,9 +1346,27 @@ bool wxTranslations::AddCatalog(const wxString& domain,
         return true;
 
     const wxString msgIdLang = wxUILocale::GetLanguageCanonicalName(msgIdLanguage);
-    const wxString domain_lang = GetBestTranslation(domain, msgIdLang);
 
-    if ( msgIdLang == domain_lang )
+    // Check if the original strings can be used directly.
+    bool canUseUntranslated = false;
+    if ( m_lang.empty() )
+    {
+        // If we are using the default language, check if the message ID
+        // language is acceptable for this system.
+        const wxString domain_lang = GetBestTranslation(domain, msgIdLang);
+
+        if ( msgIdLang == domain_lang )
+            canUseUntranslated = true;
+    }
+    else // But if we have a fixed language, we should just check it instead.
+    {
+        // Consider message IDs for another region using the same language
+        // acceptable.
+        if ( msgIdLang.BeforeFirst('_') == m_lang.BeforeFirst('_') )
+            canUseUntranslated = true;
+    }
+
+    if ( canUseUntranslated )
     {
         wxLogTrace(TRACE_I18N,
                     wxS("not using translations for domain '%s' with msgid language '%s'"),
diff --git a/tests/intl/intltest.cpp b/tests/intl/intltest.cpp
index ca3ceebdf3..9b14175fce 100644
--- a/tests/intl/intltest.cpp
+++ b/tests/intl/intltest.cpp
@@ -239,7 +239,7 @@ void IntlTestCase::IsAvailable()
     CPPUNIT_ASSERT_EQUAL( origLocale, setlocale(LC_ALL, nullptr) );
 }
 
-TEST_CASE("wxTranslations::Available", "[translations]")
+TEST_CASE("wxTranslations::AddCatalog", "[translations]")
 {
     // We currently have translations for French and Japanese in this test
     // directory, check that loading those succeeds but loading others doesn't.
@@ -270,6 +270,21 @@ TEST_CASE("wxTranslations::Available", "[translations]")
         trans.SetLanguage(wxLANGUAGE_ITALIAN);
         CHECK_FALSE( trans.AddAvailableCatalog(domain) );
     }
+
+    // And loading catalog using the same language as message IDs should
+    // "succeed" too, even if there is no such file, as in this case the
+    // message IDs themselves can be used directly.
+    SECTION("Untranslated")
+    {
+        trans.SetLanguage(wxLANGUAGE_GERMAN);
+        CHECK( trans.AddCatalog(domain, wxLANGUAGE_GERMAN) );
+
+        // Using a different region should still work.
+        CHECK( trans.AddCatalog(domain, wxLANGUAGE_GERMAN_SWISS) );
+
+        // But using a completely different language should not.
+        CHECK_FALSE( trans.AddCatalog(domain, wxLANGUAGE_DUTCH) );
+    }
 }
 
 TEST_CASE("wxLocale::Default", "[locale]")