diff --git a/Store/MongoDbStore.php b/Store/MongoDbStore.php
index acac8bc..e9ce69a 100644
--- a/Store/MongoDbStore.php
+++ b/Store/MongoDbStore.php
@@ -17,7 +17,7 @@
 use MongoDB\Database;
 use MongoDB\Driver\BulkWrite;
 use MongoDB\Driver\Command;
-use MongoDB\Driver\Exception\WriteException;
+use MongoDB\Driver\Exception\BulkWriteException;
 use MongoDB\Driver\Manager;
 use MongoDB\Driver\Query;
 use MongoDB\Exception\DriverRuntimeException;
@@ -225,7 +225,7 @@ public function save(Key $key): void
 
         try {
             $this->upsert($key, $this->initialTtl);
-        } catch (WriteException $e) {
+        } catch (BulkWriteException $e) {
             if ($this->isDuplicateKeyException($e)) {
                 throw new LockConflictedException('Lock was acquired by someone else.', 0, $e);
             }
@@ -249,7 +249,7 @@ public function putOffExpiration(Key $key, float $ttl): void
 
         try {
             $this->upsert($key, $ttl);
-        } catch (WriteException $e) {
+        } catch (BulkWriteException $e) {
             if ($this->isDuplicateKeyException($e)) {
                 throw new LockConflictedException('Failed to put off the expiration of the lock.', 0, $e);
             }
@@ -332,7 +332,7 @@ private function upsert(Key $key, float $ttl): void
         $this->getManager()->executeBulkWrite($this->namespace, $write);
     }
 
-    private function isDuplicateKeyException(WriteException $e): bool
+    private function isDuplicateKeyException(BulkWriteException $e): bool
     {
         $code = $e->getCode();
 
@@ -355,7 +355,7 @@ private function getManager(): Manager
      */
     private function createMongoDateTime(float $seconds): UTCDateTime
     {
-        return new UTCDateTime($seconds * 1000);
+        return new UTCDateTime((int) ($seconds * 1000));
     }
 
     /**