diff --git a/packages/language/src/LanguageNormalizer.php b/packages/language/src/LanguageNormalizer.php
index a19fdd170..5b524caf0 100644
--- a/packages/language/src/LanguageNormalizer.php
+++ b/packages/language/src/LanguageNormalizer.php
@@ -42,7 +42,7 @@ public static function normalizeLangCode(string $lang, string $sep = '-'): strin
 
         $a = strtolower($a);
 
-        return implode($sep, [$a, $b]);
+        return $b === '' ? $a : implode($sep, [$a, $b]);
     }
 
     public static function sanitize(string $string): string
diff --git a/packages/language/test/LanguageNormalizeTest.php b/packages/language/test/LanguageNormalizeTest.php
index f40b405d8..6053da244 100644
--- a/packages/language/test/LanguageNormalizeTest.php
+++ b/packages/language/test/LanguageNormalizeTest.php
@@ -72,7 +72,7 @@ public function toISO15897UsesUnderscoreSeparator(): void
     #[Test]
     public function normalizeLangCodeKeepsLanguageOnlyCodeWithoutRegion(): void
     {
-        self::assertEquals('en-', LanguageNormalizer::normalizeLangCode('EN'));
+        self::assertEquals('en', LanguageNormalizer::normalizeLangCode('EN'));
     }
 
     #[Test]