diff --git a/hooks_test.go b/hooks_test.go
index 31a0fb9..7d628f3 100644
--- a/hooks_test.go
+++ b/hooks_test.go
@@ -104,6 +104,35 @@ func TestRegisterLocales_Good_WithInitializedDefaultService(t *testing.T) {
 	assert.Equal(t, "loaded immediately", got)
 }
 
+func TestSetDefault_Good_LoadsQueuedRegisteredLocales(t *testing.T) {
+	registeredLocalesMu.Lock()
+	savedLocales := registeredLocales
+	savedLoaded := localesLoaded
+	registeredLocales = nil
+	localesLoaded = false
+	registeredLocalesMu.Unlock()
+	defer func() {
+		registeredLocalesMu.Lock()
+		registeredLocales = savedLocales
+		localesLoaded = savedLoaded
+		registeredLocalesMu.Unlock()
+	}()
+
+	fs := fstest.MapFS{
+		"locales/en.json": &fstest.MapFile{
+			Data: []byte(`{"queued.registration": "loaded via setdefault"}`),
+		},
+	}
+	RegisterLocales(fs, "locales")
+
+	svc, err := New()
+	require.NoError(t, err)
+	SetDefault(svc)
+
+	got := svc.T("queued.registration")
+	assert.Equal(t, "loaded via setdefault", got)
+}
+
 func TestInit_LoadsRegisteredLocales(t *testing.T) {
 	// Save and restore global service state.
 	registeredLocalesMu.Lock()
diff --git a/service.go b/service.go
index d7d1f78..3c83ccf 100644
--- a/service.go
+++ b/service.go
@@ -184,6 +184,16 @@ func Default() *Service {
 // Passing nil clears the default service.
 func SetDefault(s *Service) {
 	defaultService.Store(s)
+	if s == nil {
+		return
+	}
+	registeredLocalesMu.Lock()
+	loaded := localesLoaded
+	hasRegistrations := len(registeredLocales) > 0
+	registeredLocalesMu.Unlock()
+	if !loaded && hasRegistrations {
+		loadRegisteredLocales(s)
+	}
 }
 
 // AddLoader loads translations from a Loader into the default service.