diff --git a/plugins/newsdownloader.koplugin/main.lua b/plugins/newsdownloader.koplugin/main.lua
index 19d1cc615..c7de0e87c 100644
--- a/plugins/newsdownloader.koplugin/main.lua
+++ b/plugins/newsdownloader.koplugin/main.lua
@@ -367,7 +367,7 @@ end
 
 function NewsDownloader:onCloseDocument()
     local document_full_path = self.ui.document.file
-    if  document_full_path and news_download_dir_path == string.sub(document_full_path, 1, string.len(news_download_dir_path)) then
+    if  document_full_path and news_download_dir_path and news_download_dir_path == string.sub(document_full_path, 1, string.len(news_download_dir_path)) then
         logger.dbg("NewsDownloader: document_full_path:", document_full_path)
         logger.dbg("NewsDownloader: news_download_dir_path:", news_download_dir_path)
         logger.dbg("NewsDownloader: removing NewsDownloader file from history.")
diff --git a/plugins/send2ebook.koplugin/main.lua b/plugins/send2ebook.koplugin/main.lua
index ee7e82a2b..84cf6dbf2 100644
--- a/plugins/send2ebook.koplugin/main.lua
+++ b/plugins/send2ebook.koplugin/main.lua
@@ -213,7 +213,7 @@ end
 
 function Send2Ebook:onCloseDocument()
     local document_full_path = self.ui.document.file
-    if  document_full_path and download_dir_path == string.sub(document_full_path, 1, string.len(download_dir_path)) then
+    if  document_full_path and download_dir_path and download_dir_path == string.sub(document_full_path, 1, string.len(download_dir_path)) then
         logger.dbg("Send2Ebook: document_full_path:", document_full_path)
         logger.dbg("Send2Ebook: download_dir_path:", download_dir_path)
         logger.dbg("Send2Ebook: removing Send2Ebook file from history.")