diff --git a/modules/comment/comment.item.php b/modules/comment/comment.item.php
index ccb17bc7e..d2d1d2f86 100644
--- a/modules/comment/comment.item.php
+++ b/modules/comment/comment.item.php
@@ -584,6 +584,9 @@ class commentItem extends Object
 			}
 		}
 
+		// Prevent race condition
+		FileHandler::writeFile($thumbnail_file, '', 'w');
+
 		// Target file
 		$source_file = NULL;
 		$is_tmp_file = FALSE;
@@ -685,12 +688,6 @@ class commentItem extends Object
 			return $thumbnail_url;
 		}
 
-		// create an empty file not to attempt to generate the thumbnail afterwards
-		else
-		{
-			FileHandler::writeFile($thumbnail_file, '', 'w');
-		}
-
 		return;
 	}
 
diff --git a/modules/document/document.item.php b/modules/document/document.item.php
index ec5dc2d2a..b6d7a4140 100644
--- a/modules/document/document.item.php
+++ b/modules/document/document.item.php
@@ -829,6 +829,9 @@ class documentItem extends Object
 			else return $thumbnail_url;
 		}
 
+		// Prevent race condition
+		FileHandler::writeFile($thumbnail_file, '', 'w');
+
 		// Target File
 		$source_file = null;
 		$is_tmp_file = false;
@@ -906,8 +909,6 @@ class documentItem extends Object
 		if($is_tmp_file) FileHandler::removeFile($source_file);
 		// Return its path if a thumbnail is successfully genetated
 		if($output) return $thumbnail_url;
-		// Create an empty file not to re-generate the thumbnail
-		else FileHandler::writeFile($thumbnail_file, '','w');
 
 		return;
 	}