diff --git a/src/Monolog/Handler/DeduplicationHandler.php b/src/Monolog/Handler/DeduplicationHandler.php
index 873a4b86..2b1d0b86 100644
--- a/src/Monolog/Handler/DeduplicationHandler.php
+++ b/src/Monolog/Handler/DeduplicationHandler.php
@@ -148,7 +148,9 @@ class DeduplicationHandler extends BufferHandler
             throw new \RuntimeException('Failed to open file for reading and writing: ' . $this->deduplicationStore);
         }
 
-        flock($handle, LOCK_EX);
+        if (false === flock($handle, LOCK_EX)) {
+            return;
+        }
         $validLogs = [];
 
         $timestampValidity = time() - $this->time;