diff --git a/src/enums/MDNodaRepository.php b/src/enums/MDNodaRepository.php
index a3a2789..ebaf79f 100644
--- a/src/enums/MDNodaRepository.php
+++ b/src/enums/MDNodaRepository.php
@@ -746,11 +746,13 @@ enum MDNodaRepository implements MDValueEnumInterface, JsonSerializable {
     public static function validateBnfId(string $id):string|false {
 
         if (!is_numeric(substr($id, -1))) {
-            $validation = self::validateNumericId(substr($id, 0, -1), ["https://catalogue.bnf.fr/ark:/12148/cb"]);
+            $id = self::validateNumericId(substr($id, 0, -1), ["https://catalogue.bnf.fr/ark:/12148/cb"]) . substr($id, -1);
         }
-        else $validation = self::validateNumericId($id, ["https://catalogue.bnf.fr/ark:/12148/cb"]);
+        else $id = self::validateNumericId($id, ["https://catalogue.bnf.fr/ark:/12148/cb"]);
 
-        if ($validation === false) return false;
+        if ($id === false) {
+            return false;
+        }
 
         return $id;
 
diff --git a/tests/MDNodaRepositoryTest.php b/tests/MDNodaRepositoryTest.php
index a8acc78..f17a586 100644
--- a/tests/MDNodaRepositoryTest.php
+++ b/tests/MDNodaRepositoryTest.php
@@ -62,6 +62,17 @@ final class MDNodaRepositoryTest extends TestCase {
 
     }
 
+    /**
+     * Data provider for validating BNE IDs.
+     *
+     * @return Generator<string, array{0: string|false, 1: string}>
+     */
+    public static function bnfIdForValidationProvider():Generator {
+
+        yield "Broken input / duplicate https" => [false, "https://catalogue.bnf.fr/ark:/12148/cbhttps://catalogue.bnf.fr/ark:/12148/cbhttps://catalogue.bnf.fr/ark:/12148/cb104183522"];
+
+    }
+
     /**
      * Ensure validating references to the BNE works.
      *