diff --git a/src/Formatter/DEFormatter.php b/src/Formatter/DEFormatter.php
index 42c40f0..d587166 100644
--- a/src/Formatter/DEFormatter.php
+++ b/src/Formatter/DEFormatter.php
@@ -18,7 +18,9 @@ class DEFormatter implements CountryPostcodeFormatter
 {
     public function format(string $postcode) : ?string
     {
-        if (preg_match('/^[0-9]{5}$/', $postcode) !== 1) {
+
+        if (preg_match('/^((?:0[1-46-9]\d{3})|(?:[1-357-9]\d{4})|(?:4[0-24-9]\d{3})|(?:6[013-9]\d{3}))$/', $postcode) !== 1) {
+
             return null;
         }
 
diff --git a/src/Formatter/FRFormatter.php b/src/Formatter/FRFormatter.php
index 36f8313..8641aae 100644
--- a/src/Formatter/FRFormatter.php
+++ b/src/Formatter/FRFormatter.php
@@ -11,12 +11,19 @@
  *
  * Postcodes consist of 5 digits, without separator.
  *
+ * First two digits indicate the department (region)
+ * 01–95 for metropolitan areas
+ * 96–98 for overseas territories
+ *
  * @see https://en.wikipedia.org/wiki/List_of_postal_codes
+ * @see https://en.wikipedia.org/wiki/Postal_codes_in_France
  */
 class FRFormatter implements CountryPostcodeFormatter
 {
+
     public function format(string $postcode) : ?string
     {
+
         if (preg_match('/^[0-9]{5}$/', $postcode) !== 1) {
             return null;
         }
diff --git a/src/Formatter/ROFormatter.php b/src/Formatter/ROFormatter.php
index 55eec0a..faadc0d 100644
--- a/src/Formatter/ROFormatter.php
+++ b/src/Formatter/ROFormatter.php
@@ -18,7 +18,7 @@ class ROFormatter implements CountryPostcodeFormatter
 {
     public function format(string $postcode) : ?string
     {
-        if (preg_match('/^[0-9]{6}$/', $postcode) !== 1) {
+        if (preg_match('/^(01|02|03|04|05|06|07|08|09|10|11|12|13|14|15|16|17|18|19|20|21|22|23|24|25|26|27|28|29|30|31|32|33|34|35|36|37|38|39|40|41|42|43|44|45|50|51|52|53|54|55|60|61|62|70|71|72|73|80|81|82|90|91|92)[0-9]{4}$/', $postcode) !== 1) {
             return null;
         }
 
diff --git a/tests/Formatter/DEFormatterTest.php b/tests/Formatter/DEFormatterTest.php
index 5338dda..25c046a 100644
--- a/tests/Formatter/DEFormatterTest.php
+++ b/tests/Formatter/DEFormatterTest.php
@@ -36,6 +36,51 @@ public function providerFormat() : array
             ['ABCD', null],
             ['ABCDE', null],
             ['ABCDEF', null],
+
+            // invalid
+            ['010101', null],
+            ['000000', null],
+            ['(123456)', null],
+            ['!23456', null],
+            ['412345', null],
+            ['567890', null],
+            ['4A1234', null],
+            ['132045', null],
+            ['00001', null],
+            ['05234', null],
+            ['62000', null],
+            ['43000', null],
+
+            // valid
+            ['01234','01234'],
+            ['04123','04123'],
+            ['06123','06123'],
+            ['07123', '07123'],
+            ['08123', '08123'],
+            ['09123', '09123'],
+            ['18888', '18888'],
+            ['38888', '38888'],
+            ['58888', '58888'],
+            ['78888', '78888'],
+            ['88888', '88888'],
+            ['99999', '99999'],
+            ['40123', '40123'],
+            ['42123', '42123'],
+            ['44123', '44123'],
+            ['46123', '46123'],
+            ['47123', '47123'],
+            ['48123', '48123'],
+            ['49123', '49123'],
+            ['60123', '60123'],
+            ['61123', '61123'],
+            ['63123', '63123'],
+            ['64123', '64123'],
+            ['65123', '65123'],
+            ['66123', '66123'],
+            ['67123', '67123'],
+            ['68123', '68123'],
+            ['69123', '69123'],
+
         ];
     }
 }
diff --git a/tests/Formatter/ROFormatterTest.php b/tests/Formatter/ROFormatterTest.php
index 719bc8d..71d6a18 100644
--- a/tests/Formatter/ROFormatterTest.php
+++ b/tests/Formatter/ROFormatterTest.php
@@ -37,6 +37,29 @@ public function providerFormat() : array
             ['ABCD', null],
             ['ABCDE', null],
             ['ABCDEF', null],
+
+            // valid
+            ['010101', '010101'],
+            ['123456', '123456'],
+            ['090123', '090123'],
+            ['080456', '080456'],
+            ['070789', '070789'],
+            ['123450', '123450'],
+            ['012345', '012345'],
+            ['202020', '202020'],
+
+            // invalid
+            ['000123', null],
+            ['01111', null],
+            ['000000', null],
+            ['12ABCD', null],
+            ['12345678', null],
+            ['01 234 56', null],
+            ['0300!', null],
+            ['999999', null],
+            ['12 345', null],
+            ['07-089', null]
+
         ];
     }
 }