diff --git a/modules/system/console/WinterUtil.php b/modules/system/console/WinterUtil.php
index 1bbe6d9857..a3f609588a 100644
--- a/modules/system/console/WinterUtil.php
+++ b/modules/system/console/WinterUtil.php
@@ -194,6 +194,7 @@ protected function utilCompileLang()
             $srcPath = base_path() . '/modules/system/lang/'.$locale.'/client.php';
 
             $messages = require $fallbackPath;
+
             if (File::isFile($srcPath) && $fallbackPath != $srcPath) {
                 $messages = array_replace_recursive($messages, require $srcPath);
             }
@@ -201,11 +202,25 @@ protected function utilCompileLang()
             /*
              * Load possible replacements from /lang
              */
+            $overrides = [];
+            $parentOverrides = [];
+
             $overridePath = base_path() . '/lang/'.$locale.'/system/client.php';
             if (File::isFile($overridePath)) {
-                $messages = array_replace_recursive($messages, require $overridePath);
+                $overrides = require $overridePath;
             }
 
+            if (str_contains($locale, '-')) {
+                list($parentLocale, $country) = explode('-', $locale);
+
+                $parentOverridePath = base_path() . '/lang/'.$parentLocale.'/system/client.php';
+                if (File::isFile($parentOverridePath)) {
+                    $parentOverrides = require $parentOverridePath;
+                }
+            }
+
+            $messages = array_replace_recursive($messages, $parentOverrides, $overrides);
+
             /*
              * Compile from stub and save file
              */
diff --git a/tests/unit/system/console/WinterUtilTest.php b/tests/unit/system/console/WinterUtilTest.php
new file mode 100644
index 0000000000..9ea1c88dc8
--- /dev/null
+++ b/tests/unit/system/console/WinterUtilTest.php
@@ -0,0 +1,85 @@
+<?php
+
+class WinterUtilTest extends TestCase
+{
+    public function testCompileLang()
+    {
+        $defaultClient = base_path('/modules/system/lang/en/client.php');
+
+        // mv file so we can inject a test
+        rename($defaultClient, $defaultClient . '.backup');
+
+        file_put_contents($defaultClient, '<?php return [\'winter\' => \'is coming\'];');
+
+        // execute compile
+        $this->artisan('winter:util compile lang')->execute();
+
+        // validate default lang handling
+        $lang = file_get_contents(base_path('modules/system/assets/js/lang/lang.en.js'));
+        $this->assertStringContainsString('winter', $lang);
+        $this->assertStringContainsString('is coming', $lang);
+
+        // simulate override
+        $created = [];
+
+        foreach (['lang/en/system', 'lang/en-gb/system'] as $slug) {
+            $path = rtrim(base_path(), '/');
+            foreach (explode('/', $slug) as $dir) {
+                $path = $path . '/' . $dir;
+                if (!is_dir($path)) {
+                    mkdir($path, 0755);
+                    $created[] = $path;
+                }
+            }
+        }
+
+        $langClient = base_path('lang/en/system/client.php');
+        // handle existing file
+        if (file_exists($langClient)) {
+            rename($langClient, $langClient . '.backup');
+        }
+
+        file_put_contents($langClient, '<?php return [\'winter\' => \'is epic\'];');
+
+        $langCountryClient = base_path('lang/en-gb/system/client.php');
+        // handle existing file
+        if (file_exists($langCountryClient)) {
+            rename($langCountryClient, $langCountryClient . '.backup');
+        }
+
+        file_put_contents($langCountryClient, '<?php return [\'whats_epic\' => \'winter\'];');
+
+        // execute compile
+        $this->artisan('winter:util compile lang')->execute();
+
+        // validate override handling
+        $lang = file_get_contents(base_path('modules/system/assets/js/lang/lang.en.js'));
+        $this->assertStringContainsString('winter', $lang);
+        $this->assertStringContainsString('is epic', $lang);
+
+        // check that lang subset has included parent overrides
+        $lang = file_get_contents(base_path('modules/system/assets/js/lang/lang.en-gb.js'));
+        $this->assertStringContainsString('winter', $lang);
+        $this->assertStringContainsString('is epic', $lang);
+        $this->assertStringContainsString('whats_epic', $lang);
+        $this->assertStringContainsString('winter', $lang);
+
+        // restore
+        unlink($defaultClient);
+        rename($defaultClient . '.backup', $defaultClient);
+
+        foreach ([$langClient, $langCountryClient] as $client) {
+            unlink($client);
+            if (file_exists($client . '.backup')) {
+                rename($client . '.backup', $client);
+            }
+        }
+
+        foreach (array_reverse($created) as $dir) {
+            rmdir($dir);
+        }
+
+        // regenerate original compiled lang
+        $this->artisan('winter:util compile lang')->execute();
+    }
+}