diff --git a/build-appveyor.ps1 b/build-appveyor.ps1
new file mode 100644
index 0000000..f0646b0
--- /dev/null
+++ b/build-appveyor.ps1
@@ -0,0 +1,122 @@
+$input_rom_file        = "bin/m12fresh.gba"
+$output_rom_file       = "bin/m12.gba"
+$output_rom_file_zeros = "bin/m12-00.gba"
+$output_ips_file       = "bin/m12.ips"
+
+Function New-BlankFile([string]$path, [int]$size, [byte]$value)
+{
+    $file = [System.IO.File]::Create($path)
+    $bytes = ,$value * $size
+    $file.Write($bytes, 0, $size);
+    $file.Close()
+}
+
+Add-Type @"
+using System.IO;
+
+namespace M12
+{
+    public class Builder
+    {
+        public static void CreateIpsPatch(byte[] zeros, byte[] ones, Stream outputStream)
+        {
+            using (var writer = new BinaryWriter(outputStream))
+            {
+                writer.Write(0x43544150);
+                writer.Write((byte)0x48);
+
+                for (int i = 0; i < zeros.Length; i++)
+                {
+                    if (zeros[i] == ones[i])
+                    {
+                        bool isRun = true;
+                        int j = i + 1;
+
+                        for (; j < zeros.Length; j++)
+                        {
+                            if (zeros[j] != ones[j])
+                                break;
+
+                            if ((j - i) >= 0xFFFF)
+                            {
+                                j = i + 0xFFFF;
+                                break;
+                            }
+
+                            if ((zeros[j] != zeros[i]) && isRun)
+                                isRun = false;
+                        }
+
+                        int length = j - i;
+
+                        bool correctedForEof = false;
+
+                        if (i == 0x454F46)
+                        {
+                            i--;
+                            length++;
+                            correctedForEof = true;
+                            isRun = false;
+                        }
+
+                        WriteInt24(writer, i);
+
+                        /*if (isRun && (length > 3))
+                        {
+                            WriteInt16(writer, 0);
+                            writer.Write((byte)zeros[i]);
+                        }
+                        else*/
+                        {
+                            WriteInt16(writer, length);
+
+                            for (j = 0; j < length; j++)
+                            {
+                                writer.Write(zeros[i + j]);
+                            }
+                        }
+
+                        if (correctedForEof)
+                            i++;
+
+                        i += length - 1;
+                    }
+                }
+
+                writer.Write((ushort)0x4F45);
+                writer.Write((byte)0x46);
+            }
+        }
+
+        static void WriteInt24(BinaryWriter writer, int value)
+        {
+            writer.Write((byte)((value >> 16) & 0xFF));
+            writer.Write((byte)((value >> 8) & 0xFF));
+            writer.Write((byte)(value & 0xFF));
+        }
+
+        static void WriteInt16(BinaryWriter writer, int value)
+        {
+            writer.Write((byte)((value >> 8) & 0xFF));
+            writer.Write((byte)(value & 0xFF));
+        }
+    }
+}
+"@
+
+Function Create-Patch([string]$path1, [string]$path2, [string]$output_path)
+{
+    $bytes1 = [System.IO.File]::ReadAllBytes($path1)
+    $bytes2 = [System.IO.File]::ReadAllBytes($path2)
+    $file = [System.IO.File]::Create($output_path)
+    [M12.Builder]::CreateIpsPatch($bytes1, $bytes2, $file)
+    $file.Close()
+}
+
+.\build-tools.ps1
+New-BlankFile $input_rom_file 16777216 0
+.\build.ps1
+Copy-Item $output_rom_file -Destination $output_rom_file_zeros
+New-BlankFile $input_rom_file 16777216 255
+.\build.ps1
+Create-Patch $output_rom_file $output_rom_file_zeros $output_ips_file