diff --git a/CSharp.lua/CoreSystem.Lua/CoreSystem/Array.lua b/CSharp.lua/CoreSystem.Lua/CoreSystem/Array.lua
index 1c158808..8fc0541c 100644
--- a/CSharp.lua/CoreSystem.Lua/CoreSystem/Array.lua
+++ b/CSharp.lua/CoreSystem.Lua/CoreSystem/Array.lua
@@ -163,7 +163,7 @@ local function get(t, index)
   if v == nil then
     throw(ArgumentOutOfRangeException("index"))
   end
-  if v ~= null then 
+  if v ~= null then
     return v
   end
   return nil
diff --git a/CSharp.lua/CoreSystem.Lua/CoreSystem/Convert.lua b/CSharp.lua/CoreSystem.Lua/CoreSystem/Convert.lua
index 601b61bb..bf19c27d 100644
--- a/CSharp.lua/CoreSystem.Lua/CoreSystem/Convert.lua
+++ b/CSharp.lua/CoreSystem.Lua/CoreSystem/Convert.lua
@@ -501,13 +501,11 @@ local function fromBase64Decode(s, offset, len, t, resultLength)
     local coroutine
     local c = s:get(i + offset)
     i = i + 1
-    if c >= 65 then
-      if c <= 90 then
-        c = c - 65
-      elseif c <= 122 then
-        c = c - 71
-      end
-    elseif c >= 48 then
+    if c >= 65 and c <= 90 then
+      c = c - 65
+    elseif c >= 97 and c <= 122 then
+      c = c - 71
+    elseif c >= 48 and c <= 57 then
       c = c + 4
     else
       if c == 43 then
@@ -545,7 +543,7 @@ local function fromBase64Decode(s, offset, len, t, resultLength)
         throw(FormatException("Format_BadBase64CharArrayLength"))
       end
 
-      if j < 2 then
+      if resultLength - j < 2 then
         return - 1
       end
 
@@ -555,7 +553,7 @@ local function fromBase64Decode(s, offset, len, t, resultLength)
       codes = 0x000000ff
     else
       while i < len - 1 do
-        c = s:get(i + offset)
+        local c = s:get(i + offset)
         if c ~= 32 and c ~= 10 and c ~= 13 and c ~= 9 then
           break
         end
@@ -596,7 +594,6 @@ local function fromBase64CharPtr(s, i, n)
     n = n - 1
   end
   local resultLength = fromBase64ComputeResultLength(s, i, n)
-  print(resultLength .. " xxx")
   local t = {}
   fromBase64Decode(s, i, n, t, resultLength)
   return System.arrayFromTable(t, Byte)
diff --git a/CSharp.lua/CoreSystem.Lua/CoreSystem/String.lua b/CSharp.lua/CoreSystem.Lua/CoreSystem/String.lua
index ea6deaed..d5bba97e 100644
--- a/CSharp.lua/CoreSystem.Lua/CoreSystem/String.lua
+++ b/CSharp.lua/CoreSystem.Lua/CoreSystem/String.lua
@@ -73,13 +73,50 @@ local function checkIndex(value, startIndex, count)
   return startIndex, count, len
 end
 
+-- https://stackoverflow.com/questions/7983574/how-to-write-a-unicode-symbol-in-lua
+local bytemarkers = { {0x7FF,192}, {0xFFFF,224}, {0x1FFFFF,240} }
+local function utf8(decimal)
+  if decimal < 128 then return char(decimal) end
+  local charbytes = {}
+  for i = 1, #bytemarkers do
+    local vals = bytemarkers[i]
+    if decimal<=vals[1] then
+      for b = i + 1, 2, -1 do
+        local mod = decimal%64
+        decimal = (decimal-mod)/64
+        charbytes[b] = char(128+mod)
+      end
+      charbytes[1] = char(vals[2]+decimal)
+      break
+    end
+  end
+  return tconcat(charbytes)
+end
+
 local function ctor(String, value, startIndex, count)
   if type(value) == "number" then
     if startIndex <= 0 then throw(ArgumentOutOfRangeException("count")) end
     return rep(char(value), startIndex)
   end
   startIndex, count = checkIndex(value, startIndex, count)
-  return char(unpack(value, startIndex + 1, startIndex + count))
+  local found
+  for i = startIndex + 1, startIndex + count do
+    local c = value[i]
+    if c >= 128 then
+      found = true
+      break
+    end
+  end
+  if not found then
+    return char(unpack(value, startIndex + 1, startIndex + count))
+  end
+  local t, index = {}, 1
+  for i = startIndex + 1, startIndex + count do
+    local c = value[i]
+    t[index] = utf8(c)
+    index = index + 1
+  end
+  return tconcat(t)
 end
 
 local function get(this, index)
diff --git a/test/BridgeNetTests/Batch1/src/BasicCSharp/TestFromIssue.cs b/test/BridgeNetTests/Batch1/src/BasicCSharp/TestFromIssue.cs
index 42405786..eb954c70 100644
--- a/test/BridgeNetTests/Batch1/src/BasicCSharp/TestFromIssue.cs
+++ b/test/BridgeNetTests/Batch1/src/BasicCSharp/TestFromIssue.cs
@@ -123,6 +123,14 @@ public static void TestOf458()
                 .ToList();
         }
 
+        [Test]
+        public static void TestOf441() 
+        {
+             var input = "aGVsbG8gd29ybGQ=";
+             var bytes = Convert.FromBase64String(input);
+             Assert.AreEqual(input, Convert.ToBase64String(bytes));
+        }
+
         private class BattleModelSlotPrototype {
             public string a;
             public string b;
diff --git a/test/BridgeNetTests/Batch1/src/Convert/ConvertFromBase64Tests.cs b/test/BridgeNetTests/Batch1/src/Convert/ConvertFromBase64Tests.cs
index a9807609..8f52765e 100644
--- a/test/BridgeNetTests/Batch1/src/Convert/ConvertFromBase64Tests.cs
+++ b/test/BridgeNetTests/Batch1/src/Convert/ConvertFromBase64Tests.cs
@@ -5,7 +5,7 @@
 using Bridge.Test.NUnit;
 using System;
 
-#if false
+#if true
 namespace Bridge.ClientTest.ConvertTests
 {
     [Category(Constants.MODULE_CONVERT)]