diff --git a/src/BizHawk.Client.EmuHawk/tools/SpecializedToolAttribute.cs b/src/BizHawk.Client.EmuHawk/tools/SpecializedToolAttribute.cs
index c274a40c23..278040f3ad 100644
--- a/src/BizHawk.Client.EmuHawk/tools/SpecializedToolAttribute.cs
+++ b/src/BizHawk.Client.EmuHawk/tools/SpecializedToolAttribute.cs
@@ -6,6 +6,7 @@ namespace BizHawk.Client.EmuHawk
 	/// <summary>
 	/// Defines a <see cref="IToolForm"/> as a specialized tool that is for a specific system or core
 	/// </summary>
+	[AttributeUsage(AttributeTargets.Class)]
 	public class SpecializedToolAttribute : Attribute
 	{
 		public SpecializedToolAttribute(string displayName)