diff --git a/Source/GrasscutterTools/Game/ItemMapGroup.cs b/Source/GrasscutterTools/Game/ItemMapGroup.cs
index d62a33f..ddf296e 100644
--- a/Source/GrasscutterTools/Game/ItemMapGroup.cs
+++ b/Source/GrasscutterTools/Game/ItemMapGroup.cs
@@ -38,7 +38,7 @@ namespace GrasscutterTools.Game
                 if (categoryLineEndIndex == -1)
                     break;
 
-                var category = idNamePairs.Substring(categoryLineStartIndex + 2, categoryLineEndIndex - categoryLineStartIndex - 3).Trim();
+                var category = idNamePairs.Substring(categoryLineStartIndex + 2, categoryLineEndIndex - categoryLineStartIndex - 2).Trim();
 
                 var nextStartIndex = idNamePairs.IndexOf("//", categoryLineEndIndex);
                 if (nextStartIndex == -1)