diff --git a/src/Core/Europe/Finland/FinlandCitizenInformationExtractor.php b/src/Core/Europe/Finland/FinlandCitizenInformationExtractor.php
index 9b92a87..495ad06 100644
--- a/src/Core/Europe/Finland/FinlandCitizenInformationExtractor.php
+++ b/src/Core/Europe/Finland/FinlandCitizenInformationExtractor.php
@@ -37,15 +37,17 @@ private function getDateOfBirth(string $id): DateTime
         $dateDigits = substr($id, 0, 6);
         [$day, $month, $year] = str_split($dateDigits, 2);
 
-        $century = $id[6];
+        $separator = $id[6];
 
-        $year += match ($century) {
+        $century = match ($separator) {
             '+' => 1800,
-            '-' => 1900,
-            'A' => 2000,
-            default => throw new InvalidArgumentException("Unrecognised character $century in ID."),
+            '-', 'Y', 'X', 'W', 'V', 'U' => 1900,
+            'A', 'B', 'C', 'D', 'E', 'F' => 2000,
+            default => throw new InvalidArgumentException("Unrecognised character $separator in ID."),
         };
 
+        $year += $century;
+
         return new DateTime("$year-$month-$day");
     }
 }
diff --git a/tests/Feature/Europe/FinlandTest.php b/tests/Feature/Europe/FinlandTest.php
index b13e1a0..e895c27 100644
--- a/tests/Feature/Europe/FinlandTest.php
+++ b/tests/Feature/Europe/FinlandTest.php
@@ -47,7 +47,19 @@ protected function setUp(): void
                 'gender' => Gender::Male,
                 'dob' => new DateTime('2003-04-04'),
                 'age' => $this->calculateAge(new DateTime('2003-04-04')),
-            ]
+            ],
+            'enni' => [
+                'hetu' => '250581X948M',
+                'gender' => Gender::Female,
+                'dob' => new DateTime('1981-05-25'),
+                'age' => $this->calculateAge(new DateTime('1981-05-25')),
+            ],
+            'kalle' => [
+                'hetu' => '311005F9511',
+                'gender' => Gender::Male,
+                'dob' => new DateTime('2005-10-31'),
+                'age' => $this->calculateAge(new DateTime('2005-10-31')),
+            ],
         ];
 
         $this->invalidIds = [