diff --git a/tests/legacy/unit-tests/util/validation.php b/tests/legacy/unit-tests/util/validation.php
index 1c08b029582..21827b43d35 100644
--- a/tests/legacy/unit-tests/util/validation.php
+++ b/tests/legacy/unit-tests/util/validation.php
@@ -123,7 +123,15 @@ class WC_Tests_Validation extends WC_Unit_Test_Case {
 			array( false, WC_Validation::is_postcode( '7850', 'BA' ) ),
 		);
 
-		return array_merge( $it, $gb, $us, $ch, $br, $ca, $nl, $si, $ba );
+		$jp = array(
+			array( true, WC_Validation::is_postcode( '1340088', 'JP' ) ),
+			array( true, WC_Validation::is_postcode( '134-0088', 'JP' ) ),
+			array( false, WC_Validation::is_postcode( '1340-088', 'JP' ) ),
+			array( false, WC_Validation::is_postcode( '12345', 'JP' ) ),
+			array( false, WC_Validation::is_postcode( '0123', 'JP' ) ),
+		);
+
+		return array_merge( $it, $gb, $us, $ch, $br, $ca, $nl, $si, $ba, $jp );
 	}
 
 	/**