diff --git a/src/Plugin/KeyProvider/ConfigKeyProvider.php b/src/Plugin/KeyProvider/ConfigKeyProvider.php
index cd362c5..3d128aa 100644
--- a/src/Plugin/KeyProvider/ConfigKeyProvider.php
+++ b/src/Plugin/KeyProvider/ConfigKeyProvider.php
@@ -91,7 +91,9 @@ class ConfigKeyProvider extends KeyProviderBase implements KeyPluginFormInterfac
       $key_value = base64_encode($key_value);
     }
 
-    if ($this->configuration['key_value'] = $key_value) {
+    $this->configuration['key_value'] = $key_value;
+
+    if (isset($this->configuration['key_value'])) {
       return TRUE;
     }
     else {