diff --git a/src/I18n/PluralRules.php b/src/I18n/PluralRules.php
index 606194064c9..f1a53478700 100644
--- a/src/I18n/PluralRules.php
+++ b/src/I18n/PluralRules.php
@@ -170,8 +170,8 @@ public static function calculate($locale, $n) {
 				return $n % 10 == 1 ? 0 : ($n % 10 == 2 ? 1 : 2);
 			case 9:
 				return $n == 1 ? 0 :
-					$n == 0 || ($n % 100 > 0 && $n % 100 <= 10) ? 1 :
-					$n % 100 > 10 && $n % 100 < 20 ? 2 : 3;
+					($n == 0 || ($n % 100 > 0 && $n % 100 <= 10) ? 1 :
+					($n % 100 > 10 && $n % 100 < 20 ? 2 : 3));
 			case 10:
 				return $n %10 == 1 && $n % 100 != 11 ? 1 : $n == 0 ? 0 : 2;
 			case 11:
diff --git a/tests/TestCase/I18n/PluralRulesTest.php b/tests/TestCase/I18n/PluralRulesTest.php
index 56f4eeb3f86..e5d99bcb26e 100644
--- a/tests/TestCase/I18n/PluralRulesTest.php
+++ b/tests/TestCase/I18n/PluralRulesTest.php
@@ -70,7 +70,12 @@ public function localesProvider() {
 			['mk', 0, 2],
 			['mk', 1, 0],
 			['mk', 13, 2],
-			['mk', 21, 0]
+			['mt', 0, 1],
+			['mt', 1, 0],
+			['mt', 11, 2],
+			['mt', 13, 2],
+			['mt', 21, 3],
+			['mt', 102, 1]
 		];
 	}