diff --git a/Store/PdoStore.php b/Store/PdoStore.php
index 79fe680..3eeb83b 100644
--- a/Store/PdoStore.php
+++ b/Store/PdoStore.php
@@ -24,7 +24,7 @@
  *
  * Lock metadata are stored in a table. You can use createTable() to initialize
  * a correctly defined table.
-
+ *
  * CAUTION: This store relies on all client and server nodes to have
  * synchronized clocks for lock expiry to occur at the correct time.
  * To ensure locks don't expire prematurely; the TTLs should be set with enough
@@ -40,8 +40,8 @@ class PdoStore implements PersistingStoreInterface
     private $conn;
     private $dsn;
     private $driver;
-    private $username = '';
-    private $password = '';
+    private $username = null;
+    private $password = null;
     private $connectionOptions = [];
 
     private $dbalStore;
diff --git a/Store/PostgreSqlStore.php b/Store/PostgreSqlStore.php
index 6c78386..4332969 100644
--- a/Store/PostgreSqlStore.php
+++ b/Store/PostgreSqlStore.php
@@ -29,8 +29,8 @@ class PostgreSqlStore implements BlockingSharedLockStoreInterface, BlockingStore
 {
     private $conn;
     private $dsn;
-    private $username = '';
-    private $password = '';
+    private $username = null;
+    private $password = null;
     private $connectionOptions = [];
     private static $storeRegistry = [];