diff --git a/CHANGELOG.md b/CHANGELOG.md
index d8162bfb..8b93e9c8 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -11,6 +11,10 @@ before starting to add changes. Use example [placed in the end of the page](#exa
 
 ## [Unreleased]
 
+## [3.13.1] 2023-10-19
+
+- Checking CPR format before fetching data
+
 ## [3.13.0] 2023-10-11
 
 - [#62](https://github.com/OS2Forms/os2forms/pull/62)
diff --git a/modules/os2forms_nemid/src/Element/NemidCprFetchData.php b/modules/os2forms_nemid/src/Element/NemidCprFetchData.php
index 1dc01d27..5c20fbb8 100644
--- a/modules/os2forms_nemid/src/Element/NemidCprFetchData.php
+++ b/modules/os2forms_nemid/src/Element/NemidCprFetchData.php
@@ -9,6 +9,18 @@
  */
 class NemidCprFetchData extends CompositeFetchDataBase {
 
+  /**
+   * {@inheritdoc}
+   */
+  public static function getCompositeElements(array $element) {
+    $elements = parent::getCompositeElements($element);
+
+    // Pattern for CPR.
+    $elements[self::getValueElementName()]['#pattern'] = '\d{6}-\d{4}';
+
+    return $elements;
+  }
+
   /**
    * {@inheritdoc}
    */