diff --git a/crereader.lua b/crereader.lua
index fa654b5e4..36956fcaf 100644
--- a/crereader.lua
+++ b/crereader.lua
@@ -30,10 +30,20 @@ end
 function CREReader:open(filename)
 	local ok
 	local file_type = string.lower(string.match(filename, ".+%.([^.]+)"))
+
 	-- these two format use the same css file
 	if file_type == "html" then
 		file_type = "htm"
 	end
+
+	-- detect file type for documents inside zip file
+	if file_type == "zip" then
+		-- store filename without zip-extention to fn
+		local fn = string.lower(string.sub(filename,0,-4))
+		-- if no double extention then default file_type
+		file_type = string.lower(string.match(fn, ".+%.([^.]+)") or "fb2")
+	end 
+
 	local style_sheet = "./data/"..file_type..".css"
 	ok, self.doc = pcall(cre.openDocument, filename, style_sheet, 
 						G_width, G_height)