From 9be82da44951c5b0389592369be0dcca65527e1a Mon Sep 17 00:00:00 2001
From: Hzj_jie <Hzj_jie@hotmail.com>
Date: Thu, 29 Nov 2018 10:29:14 -0800
Subject: [PATCH] Lower file suffix (#4369)

---
 frontend/document/documentregistry.lua | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/frontend/document/documentregistry.lua b/frontend/document/documentregistry.lua
index 22bda7ceb..c00651274 100644
--- a/frontend/document/documentregistry.lua
+++ b/frontend/document/documentregistry.lua
@@ -13,6 +13,7 @@ local DocumentRegistry = {
 }
 
 function DocumentRegistry:addProvider(extension, mimetype, provider, weight)
+    extension = string.lower(extension)
     table.insert(self.providers, {
         extension = extension,
         mimetype = mimetype,
@@ -53,7 +54,7 @@ end
 -- @string file
 -- @treturn boolean
 function DocumentRegistry:hasProvider(file)
-    local filename_suffix = util.getFileNameSuffix(file)
+    local filename_suffix = string.lower(util.getFileNameSuffix(file))
 
     if self.filetype_provider[filename_suffix] then
         return true