diff --git a/CHANGELOG.md b/CHANGELOG.md
index 00b5917..58c2f71 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,7 @@
+# Concealment 1.2.1
+* Fixes
+    - Fixed off-by-one crash in RevealGrids()
+
 # Concealment 1.2
 * Features
     - Added option to exempt pirate-owned grids
diff --git a/Concealment/ConcealmentPlugin.cs b/Concealment/ConcealmentPlugin.cs
index 9039223..257086a 100644
--- a/Concealment/ConcealmentPlugin.cs
+++ b/Concealment/ConcealmentPlugin.cs
@@ -31,7 +31,7 @@
 
 namespace Concealment
 {
-    [Plugin("Concealment", "1.2", "17f44521-b77a-4e85-810f-ee73311cf75d")]
+    [Plugin("Concealment", "1.2.1", "17f44521-b77a-4e85-810f-ee73311cf75d")]
     public sealed class ConcealmentPlugin : TorchPluginBase, IWpfPlugin
     {
         public Persistent<Settings> Settings { get; private set; }
@@ -311,7 +311,7 @@ public int RevealGrids(double distanceFromPlayers)
 
             if (_settingsChanged)
             {
-                for (var i = ConcealedGroups.Count; i >= 0; i--)
+                for (var i = ConcealedGroups.Count - 1; i >= 0; i--)
                 {
                     if (IsExcluded(ConcealedGroups[i]))
                         revealed += RevealGroup(ConcealedGroups[i]);