diff --git a/application/controllers/ConfigController.php b/application/controllers/ConfigController.php
index 52a2a385..67a642a2 100644
--- a/application/controllers/ConfigController.php
+++ b/application/controllers/ConfigController.php
@@ -4,6 +4,7 @@
 
 namespace Icinga\Module\Kubernetes\Controllers;
 
+use Exception;
 use GuzzleHttp\Psr7\ServerRequest;
 use Icinga\Application\Config;
 use Icinga\Application\Logger;
@@ -198,72 +199,84 @@ public function prometheusAction()
         $data = [];
 
         foreach ($dbConfig as $pair) {
-            switch ($pair->key) {
-                case self::PROMETHEUS_URL:
-                    $data['prometheus_url'] = $pair->value;
-                    break;
-                case self::PROMETHEUS_USERNAME:
-                    $data['prometheus_username'] = $pair->value;
-                    break;
-                case self::PROMETHEUS_PASSWORD:
-                    $data['prometheus_password'] = $pair->value;
-                    break;
-            }
+            $data[str_replace('.', '_', $pair->key)] = $pair->value;
         }
 
         $form = (new PrometheusConfigForm())
             ->populate($data)
-            ->on(PrometheusConfigForm::ON_SUCCESS, function ($form) use ($db, $data) {
+            ->on(PrometheusConfigForm::ON_SUCCESS, function ($form) use ($db, $dbConfig) {
                 if ($form->isLocked()) {
                     Notification::error($this->translate('Prometheus configuration is locked'));
                     return;
                 }
 
-                if (isset($data['prometheus_url'])) {
-                    $db->update('config',
-                        ['value' => $form->getValue('prometheus_url')],
-                        [$db->quoteIdentifier('key') . ' = ?' => self::PROMETHEUS_URL]
-                    );
-                } else {
-                    $db->insert('config',
-                        [
-                            $db->quoteIdentifier('key') => self::PROMETHEUS_URL,
-                            'value'                     => $form->getValue('prometheus_url')
-                        ]
-                    );
-                }
+                try {
+                    $db->exec("SET TRANSACTION ISOLATION LEVEL SERIALIZABLE");
+                    $db->beginTransaction();
 
-                if (isset($data['prometheus_username'])) {
-                    $db->update('config',
-                        ['value' => $form->getValue('prometheus_username')],
-                        [$db->quoteIdentifier('key') . ' = ?' => self::PROMETHEUS_USERNAME]
-                    );
-                } else {
-                    $db->insert('config',
-                        [
-                            $db->quoteIdentifier('key') => self::PROMETHEUS_USERNAME,
-                            'value'                     => $form->getValue('prometheus_username')
-                        ]
-                    );
-                }
+                    $data = [];
 
-                if (isset($data['prometheus_password'])) {
-                    $db->update('config',
-                        ['value' => $form->getValue('prometheus_password')],
-                        [$db->quoteIdentifier('key') . ' = ?' => self::PROMETHEUS_PASSWORD]
-                    );
-                } else {
-                    $db->insert('config',
-                        [
-                            $db->quoteIdentifier('key') => self::PROMETHEUS_PASSWORD,
-                            'value'                     => $form->getValue('prometheus_password')
-                        ]
-                    );
-                }
+                    foreach ($dbConfig as $pair) {
+                        $data[$pair->key] = ['value' => $pair->value, 'locked' => $pair->locked];
+                    }
 
-                $this->redirectNow('__REFRESH__');
+                    if ($data[self::PROMETHEUS_URL]['locked'] !== 'y') {
+                        if (isset($data[self::PROMETHEUS_URL])) {
+                            $db->update('config',
+                                ['value' => $form->getValue($this->fieldForForm(self::PROMETHEUS_URL))],
+                                [$db->quoteIdentifier('key') . ' = ?' => self::PROMETHEUS_URL]
+                            );
+                        } else {
+                            $db->insert('config',
+                                [
+                                    $db->quoteIdentifier('key') => self::PROMETHEUS_URL,
+                                    'value'                     => $form->getValue($this->fieldForForm(self::PROMETHEUS_URL))
+                                ]
+                            );
+                        }
+                    }
+
+                    if ($data[self::PROMETHEUS_USERNAME]['locked'] !== 'y') {
+                        if (isset($data[self::PROMETHEUS_USERNAME])) {
+                            $db->update('config',
+                                ['value' => $form->getValue($this->fieldForForm(self::PROMETHEUS_USERNAME))],
+                                [$db->quoteIdentifier('key') . ' = ?' => self::PROMETHEUS_USERNAME]
+                            );
+                        } else {
+                            $db->insert('config',
+                                [
+                                    $db->quoteIdentifier('key') => self::PROMETHEUS_USERNAME,
+                                    'value'                     => $form->getValue($this->fieldForForm(self::PROMETHEUS_USERNAME))
+                                ]
+                            );
+                        }
+                    }
+
+                    if ($data[self::PROMETHEUS_PASSWORD]['locked'] !== 'y') {
+                        if (isset($data[self::PROMETHEUS_PASSWORD])) {
+                            $db->update('config',
+                                ['value' => $form->getValue($this->fieldForForm(self::PROMETHEUS_PASSWORD))],
+                                [$db->quoteIdentifier('key') . ' = ?' => self::PROMETHEUS_PASSWORD]
+                            );
+                        } else {
+                            $db->insert('config',
+                                [
+                                    $db->quoteIdentifier('key') => self::PROMETHEUS_PASSWORD,
+                                    'value'                     => $form->getValue($this->fieldForForm(self::PROMETHEUS_PASSWORD))
+                                ]
+                            );
+                        }
+                    }
+
+                    $db->commitTransaction();
+                } catch (Exception $_) {
+                    $db->rollBackTransaction();
+                    Notification::error($this->translate('Failed to store new configuration'));
+                    return;
+                }
 
                 Notification::success($this->translate('New configuration has successfully been stored'));
+                $this->redirectNow('__REFRESH__');
             })->handleRequest($this->getServerRequest());
 
         $this->mergeTabs($this->Module()->getConfigTabs()->activate('prometheus'));
@@ -271,6 +284,18 @@ public function prometheusAction()
         $this->addContent($form);
     }
 
+    /**
+     * Convert database field name to form field name
+     *
+     * @param string $field
+     *
+     * @return string
+     */
+    protected function fieldForForm(string $field): string
+    {
+        return str_replace('.', '_', $field);
+    }
+
     /**
      * Merge tabs with other tabs contained in this tab panel
      *
diff --git a/application/forms/PrometheusConfigForm.php b/application/forms/PrometheusConfigForm.php
index 4ab78a36..4b9c87bd 100644
--- a/application/forms/PrometheusConfigForm.php
+++ b/application/forms/PrometheusConfigForm.php
@@ -4,15 +4,13 @@
 
 namespace Icinga\Module\Kubernetes\Forms;
 
-use Icinga\Data\ResourceFactory;
+use Icinga\Module\Kubernetes\Common\Database;
 use Icinga\Module\Kubernetes\Controllers\ConfigController;
+use Icinga\Module\Kubernetes\Model\Config;
 use ipl\Html\Attributes;
 use ipl\Html\Html;
-use ipl\Html\HtmlElement;
-use ipl\Web\Compat\CompatForm;
-use Icinga\Module\Kubernetes\Model\Config;
 use ipl\Stdlib\Filter;
-use Icinga\Module\Kubernetes\Common\Database;
+use ipl\Web\Compat\CompatForm;
 
 class PrometheusConfigForm extends CompatForm
 {
@@ -22,7 +20,7 @@ protected function assemble(): void
             $this->addHtml(
                 Html::tag('div', Attributes::create(['class' => 'control-group']), [
                     Html::tag(
-                      'div',
+                        'div',
                         Attributes::create(['class' => 'control-label-group']),
                     ),
                     Html::tag(
@@ -41,7 +39,6 @@ protected function assemble(): void
                 'label'    => $this->translate('URL'),
                 'required' => true,
                 'disabled' => $this->isLocked(),
-                'value'    => ''
             ]
         );
 
@@ -51,7 +48,6 @@ protected function assemble(): void
             [
                 'label'    => $this->translate('Username'),
                 'disabled' => $this->isLocked(),
-                'value'    => ''
             ]
         );
 
@@ -61,7 +57,6 @@ protected function assemble(): void
             [
                 'label'    => $this->translate('Password'),
                 'disabled' => $this->isLocked(),
-                'value'    => ''
             ]
         );
 
@@ -69,7 +64,7 @@ protected function assemble(): void
             'submit',
             'submit',
             [
-                'label' => $this->translate('Save Changes'),
+                'label'    => $this->translate('Save Changes'),
                 'disabled' => $this->isLocked()
             ]
         );