diff --git a/src/editor/iofilters.lua b/src/editor/iofilters.lua
index dd86469a15..4fed4a2483 100644
--- a/src/editor/iofilters.lua
+++ b/src/editor/iofilters.lua
@@ -9,13 +9,13 @@ output = function (fpath, content)
 	-- only simple cases are handled (umlauts)
 	local chr = ("string").char
 	local charconv = {
-		[chr(164)] = chr(132), -- �
-		[chr(182)] = chr(148), -- �
-		[chr(188)] = chr(129), -- �
-		[chr(132)] = chr(142), -- �
-		[chr(150)] = chr(153), -- �
-		[chr(156)] = chr(154), -- �
-		[chr(159)] = chr(225), -- �
+		[chr(164)] = chr(228), -- ä
+		[chr(182)] = chr(246), -- ö
+		[chr(188)] = chr(252), -- ü
+		[chr(132)] = chr(196), -- Ä
+		[chr(150)] = chr(214), -- Ö
+		[chr(156)] = chr(220), -- Ü
+		[chr(159)] = chr(223), -- ß
 	}
 	return content : gsub (utf8escape.."(.)",charconv)
 end,
@@ -27,13 +27,13 @@ input = function (fpath, content)
 	local utf8escape = ("string").char(195)
 	local chr = ("string").char
 	local charconv = {
-		[chr(132)] = utf8escape..chr(164), -- �
-		[chr(148)] = utf8escape..chr(182), -- �
-		[chr(129)] = utf8escape..chr(188), -- �
-		[chr(142)] = utf8escape..chr(132), -- �
-		[chr(153)] = utf8escape..chr(150), -- �
-		[chr(154)] = utf8escape..chr(156), -- �
-		[chr(225)] = utf8escape..chr(159), -- �
+		[chr(228)] = utf8escape..chr(164), -- ä
+		[chr(246)] = utf8escape..chr(182), -- ö
+		[chr(252)] = utf8escape..chr(188), -- ü
+		[chr(196)] = utf8escape..chr(132), -- Ä
+		[chr(214)] = utf8escape..chr(150), -- Ö
+		[chr(220)] = utf8escape..chr(156), -- Ü
+		[chr(223)] = utf8escape..chr(159), -- ß
 	}
 	local lst = "["
 	for k in pairs(charconv) do lst = lst .. k end
@@ -44,10 +44,10 @@ end,
 
 }
 
---���
+--üäß
 
 for i,filter in pairs(ide.iofilters) do
-	assert(filter.output("",filter.input("","�������")),"�������","UTF8-ANSI conversion failed: "..(i))
+	assert(filter.output("",filter.input("","äöüÄÖÜß")),"„”äöüÄÖÜß","UTF8-ANSI conversion failed: "..(i))
 end
 
 -- which: "input" or "output"