diff --git a/src/Cache/SharedMemory.php b/src/Cache/SharedMemory.php
index e96e66b..6fdb7be 100644
--- a/src/Cache/SharedMemory.php
+++ b/src/Cache/SharedMemory.php
@@ -65,8 +65,8 @@ public function attach($file = __FILE__)
                 throw new \RuntimeException("file is not exists and it can not be created. file: {$file}");
             }
         }
-        $key = ftok($file, 'a');
-        $this->shm = shm_attach($key, $this->size); //allocate shared memory
+        
+        $this->shm = shm_attach(fileinode($file), $this->size); //allocate shared memory
     }
 
     /**
@@ -173,4 +173,4 @@ public function __wakeup()
     {
         $this->attach();
     }
-}
\ No newline at end of file
+}