diff --git a/ArcFormats/ImageMCG.cs b/ArcFormats/ImageMCG.cs
index 3feb3c50..b459c41c 100644
--- a/ArcFormats/ImageMCG.cs
+++ b/ArcFormats/ImageMCG.cs
@@ -26,9 +26,9 @@
 using System;
 using System.Collections.Generic;
 using System.ComponentModel.Composition;
-using System.Diagnostics;
 using System.IO;
 using System.Windows.Media;
+using GameRes.Formats.Properties;
 using GameRes.Utility;
 
 namespace GameRes.Formats.FC01
@@ -102,6 +102,7 @@ namespace GameRes.Formats.FC01
         uint    m_width;
         uint    m_height;
         uint    m_pixels;
+        byte    m_key;
 
         public byte[] Data { get { return m_output; } }
 
@@ -115,6 +116,7 @@ namespace GameRes.Formats.FC01
             m_height = info.Height;
             m_pixels = m_width*m_height;
             m_output = new byte[m_pixels*3];
+            m_key = Settings.Default.MCGLastKey;
         }
 
         static readonly byte[] ChannelOrder = { 1, 0, 2 };
@@ -122,9 +124,9 @@ namespace GameRes.Formats.FC01
         public void Unpack ()
         {
             var reader = new MrgDecoder (m_input, 0, m_pixels);
-            for (int key = 0; key < 0x100; ++key)
+            do
             {
-                reader.ResetKey ((byte)key);
+                reader.ResetKey (m_key);
                 try
                 {
                     for (int i = 0; i < 3; ++i)
@@ -141,18 +143,19 @@ namespace GameRes.Formats.FC01
                 }
                 catch (InvalidFormatException)
                 {
+                    m_key++;
                     continue;
                 }
                 Transform();
+                Settings.Default.MCGLastKey = m_key;
                 return;
             }
+            while (m_key != Settings.Default.MCGLastKey);
             throw new UnknownEncryptionScheme();
         }
 
         void Transform ()
         {
-            // esi = m_input
-            // dst = m_output
             uint dst = 0;
             uint stride = (m_width - 1) * 3;
             for (uint y = m_height-1; y > 0; --y) // @@1a
diff --git a/ArcFormats/Properties/AssemblyInfo.cs b/ArcFormats/Properties/AssemblyInfo.cs
index fc62dbc4..9bbba203 100644
--- a/ArcFormats/Properties/AssemblyInfo.cs
+++ b/ArcFormats/Properties/AssemblyInfo.cs
@@ -32,5 +32,5 @@ using System.Runtime.InteropServices;
 // You can specify all the values or you can default the Build and Revision Numbers 
 // by using the '*' as shown below:
 // [assembly: AssemblyVersion("1.0.*")]
-[assembly: AssemblyVersion ("1.0.7.79")]
-[assembly: AssemblyFileVersion ("1.0.7.79")]
+[assembly: AssemblyVersion ("1.0.7.80")]
+[assembly: AssemblyFileVersion ("1.0.7.80")]
diff --git a/ArcFormats/Properties/Settings.Designer.cs b/ArcFormats/Properties/Settings.Designer.cs
index 4c44636b..0de953b7 100644
--- a/ArcFormats/Properties/Settings.Designer.cs
+++ b/ArcFormats/Properties/Settings.Designer.cs
@@ -381,5 +381,17 @@ namespace GameRes.Formats.Properties {
                 this["ISFScheme"] = value;
             }
         }
+        
+        [global::System.Configuration.UserScopedSettingAttribute()]
+        [global::System.Diagnostics.DebuggerNonUserCodeAttribute()]
+        [global::System.Configuration.DefaultSettingValueAttribute("0")]
+        public byte MCGLastKey {
+            get {
+                return ((byte)(this["MCGLastKey"]));
+            }
+            set {
+                this["MCGLastKey"] = value;
+            }
+        }
     }
 }
diff --git a/ArcFormats/Properties/Settings.settings b/ArcFormats/Properties/Settings.settings
index 0685eef3..ae03c51c 100644
--- a/ArcFormats/Properties/Settings.settings
+++ b/ArcFormats/Properties/Settings.settings
@@ -92,5 +92,8 @@
     <Setting Name="ISFScheme" Type="System.String" Scope="User">
       <Value Profile="(Default)" />
     </Setting>
+    <Setting Name="MCGLastKey" Type="System.Byte" Scope="User">
+      <Value Profile="(Default)">0</Value>
+    </Setting>
   </Settings>
 </SettingsFile>
\ No newline at end of file
diff --git a/ArcFormats/app.config b/ArcFormats/app.config
index 5944f914..67fefa59 100644
--- a/ArcFormats/app.config
+++ b/ArcFormats/app.config
@@ -94,6 +94,9 @@
             <setting name="ISFScheme" serializeAs="String">
                 <value />
             </setting>
+            <setting name="MCGLastKey" serializeAs="String">
+                <value>0</value>
+            </setting>
         </GameRes.Formats.Properties.Settings>
     </userSettings>
 <startup><supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5"/></startup></configuration>