Index: /usr/ports/net-im/prosody/files/patch-plugins_mod__http__files.lua
===================================================================
--- /usr/ports/net-im/prosody/files/patch-plugins_mod__http__files.lua	(nonexistent)
+++ /usr/ports/net-im/prosody/files/patch-plugins_mod__http__files.lua	(working copy)
@@ -0,0 +1,11 @@
+--- plugins/mod_http_files.lua	2020-01-02 12:49:37.000000000 +0300
++++ plugins/mod_http_files.lua	2020-03-06 00:54:03.347542000 +0300
+@@ -112,7 +112,7 @@
+ 		local last_modified = os_date('!%a, %d %b %Y %H:%M:%S GMT', attr.modification);
+ 		response_headers.last_modified = last_modified;
+ 
+-		local etag = ('"%02x-%x-%x-%x"'):format(attr.dev or 0, attr.ino or 0, attr.size or 0, attr.modification or 0);
++		local etag = ('"%02x-%x-%x-%x"'):format(math.abs(attr.dev or 0), attr.ino or 0, attr.size or 0, attr.modification or 0);
+ 		response_headers.etag = etag;
+ 
+ 		local if_none_match = request_headers.if_none_match