diff --git a/Civi/Api4/Query/SqlExpression.php b/Civi/Api4/Query/SqlExpression.php
index de05876e4894..a58a580a73f9 100644
--- a/Civi/Api4/Query/SqlExpression.php
+++ b/Civi/Api4/Query/SqlExpression.php
@@ -68,6 +68,26 @@ public function __construct(string $expr, $alias = NULL) {
 
   abstract protected function initialize();
 
+  private static function munge($name, $char = '_', $len = 63) {
+    // Replace all white space and non-alpha numeric with $char
+    // we only use the ascii character set since mysql does not create table names / field names otherwise
+    // CRM-11744
+    $name = preg_replace('/[^a-zA-Z0-9_]+/', $char, trim($name));
+
+    // If there are no ascii characters present.
+    if (!strlen(trim($name, $char))) {
+      $name = \CRM_Utils_String::createRandom($len, \CRM_Utils_String::ALPHANUMERIC);
+    }
+
+    if ($len) {
+      // lets keep variable names short
+      return substr($name, 0, $len);
+    }
+    else {
+      return $name;
+    }
+  }
+
   /**
    * Converts a string to a SqlExpression object.
    *
@@ -82,7 +102,7 @@ abstract protected function initialize();
   public static function convert(string $expression, $parseAlias = FALSE, $mustBe = []) {
     $as = $parseAlias ? strrpos($expression, ' AS ') : FALSE;
     $expr = $as ? substr($expression, 0, $as) : $expression;
-    $alias = $as ? \CRM_Utils_String::munge(substr($expression, $as + 4), '_', 256) : NULL;
+    $alias = $as ? self::munge(substr($expression, $as + 4), '_', 256) : NULL;
     $bracketPos = strpos($expr, '(');
     $firstChar = substr($expr, 0, 1);
     $lastChar = substr($expr, -1);
diff --git a/ext/search_kit/tests/phpunit/api/v4/SearchDisplay/SearchRunWithCustomFieldTest.php b/ext/search_kit/tests/phpunit/api/v4/SearchDisplay/SearchRunWithCustomFieldTest.php
index 2cf32ba633b5..ac81e735ed8b 100644
--- a/ext/search_kit/tests/phpunit/api/v4/SearchDisplay/SearchRunWithCustomFieldTest.php
+++ b/ext/search_kit/tests/phpunit/api/v4/SearchDisplay/SearchRunWithCustomFieldTest.php
@@ -502,4 +502,90 @@ public function testEntityReferenceJoins() {
     $this->assertEquals('Dewey', $result[0]['columns'][0]['val']);
   }
 
+  public function testJoinWithCustomFieldEndingIn_() {
+    $subject = uniqid(__FUNCTION__);
+
+    $contact = Contact::create(FALSE)
+      ->execute()->single();
+
+    // CustomGroup based on Activity Type
+    CustomGroup::create(FALSE)
+      ->addValue('extends', 'Activity')
+      ->addValue('title', 'testactivity2')
+      ->addChain('field', CustomField::create()
+        ->addValue('custom_group_id', '$id')
+        ->addValue('label', 'testactivity_')
+        ->addValue('data_type', 'Boolean')
+        ->addValue('html_type', 'Radio')
+      )
+      ->execute();
+
+    $sampleData = [
+      ['activity_type_id:name' => 'Meeting', 'testactivity2.testactivity_' => TRUE],
+    ];
+    $this->saveTestRecords('Activity', [
+      'defaults' => ['subject' => $subject, 'source_contact_id', $contact['id']],
+      'records' => $sampleData,
+    ]);
+
+    $params = [
+      'checkPermissions' => FALSE,
+      'return' => 'page:1',
+      'savedSearch' => [
+        'api_entity' => 'Contact',
+        'api_params' => [
+          'version' => 4,
+          'select' => [
+            'id',
+            'GROUP_CONCAT(DISTINCT Contact_ActivityContact_Activity_01.testactivity2.testactivity_:label) AS GROUP_CONCAT_Contact_ActivityContact_Activity_01_testactivity2_testactivity__label',
+          ],
+          'orderBy' => [],
+          'where' => [['contact_type:name', '=', 'Individual']],
+          'groupBy' => ['id'],
+          'join' => [
+            ['Activity AS Contact_ActivityContact_Activity_01', 'INNER', 'ActivityContact',
+              ['id', '=', 'Contact_ActivityContact_Activity_01.contact_id'],
+              ['Contact_ActivityContact_Activity_01.record_type_id:name', '=', '"Activity Source"'],
+              ['Contact_ActivityContact_Activity_01.activity_type_id:name', '=', '"Meeting"'],
+            ],
+          ],
+          'having' => [],
+        ],
+      ],
+      'display' => [
+        'type' => 'table',
+        'label' => '',
+        'settings' => [
+          'actions' => TRUE,
+          'pager' => [],
+          'columns' => [
+            [
+              'type' => 'field',
+              'key' => 'id',
+              'dataType' => 'Integer',
+              'label' => 'Contact ID',
+              'sortable' => TRUE,
+            ],
+            [
+              'type' => 'field',
+              'key' => 'GROUP_CONCAT_Contact_ActivityContact_Activity_01_testactivity2_testactivity__label',
+              'dataType' => 'Boolean',
+              'label' => '(List) Contact Activities: testactivity2: testactivity_',
+              'sortable' => TRUE,
+            ],
+          ],
+          'sort' => [
+            ['id', 'ASC'],
+          ],
+        ],
+      ],
+      'afform' => NULL,
+    ];
+
+    $result = civicrm_api4('SearchDisplay', 'run', $params);
+
+    $this->assertArrayHasKey('GROUP_CONCAT_Contact_ActivityContact_Activity_01_testactivity2_testactivity__label', $result[0]['data']);
+    $this->assertEquals('Yes', $result[0]['data']['GROUP_CONCAT_Contact_ActivityContact_Activity_01_testactivity2_testactivity__label'][0]);
+  }
+
 }