diff --git a/BizHawk.Client.EmuHawk/ToolAttribute.cs b/BizHawk.Client.EmuHawk/ToolAttribute.cs
index 1ba2a2c1ef..721fa0cf48 100644
--- a/BizHawk.Client.EmuHawk/ToolAttribute.cs
+++ b/BizHawk.Client.EmuHawk/ToolAttribute.cs
@@ -6,14 +6,17 @@ namespace BizHawk.Client.EmuHawk
 	[AttributeUsage(AttributeTargets.Class)]
 	public class ToolAttribute : Attribute
 	{
-		public ToolAttribute(bool released, string[] supportedSystems)
+		public ToolAttribute(bool released, string[] supportedSystems, string[] unsupportedCores = null)
 		{
 			Released = released;
 			SupportedSystems = supportedSystems;
+            UnsupportedCores = unsupportedCores;
 		}
 
 		public bool Released { get; private set; }
 
 		public IEnumerable<string> SupportedSystems { get; private set; }
+
+        public IEnumerable<string> UnsupportedCores { get; private set; }
 	}
 }
diff --git a/BizHawk.Client.EmuHawk/tools/GameShark.cs b/BizHawk.Client.EmuHawk/tools/GameShark.cs
index ffd91c12fb..027630daf2 100644
--- a/BizHawk.Client.EmuHawk/tools/GameShark.cs
+++ b/BizHawk.Client.EmuHawk/tools/GameShark.cs
@@ -20,7 +20,8 @@ namespace BizHawk.Client.EmuHawk
 	//Verify all wording in the error reports
 
 
-	[Tool(released: true, supportedSystems: new[] { "GB", "GBA", "GEN", "N64", "NES", "PSX", "SAT", "SMS", "SNES" })]
+	[Tool(released: true, supportedSystems: new[] { "GB", "GBA", "GEN", "N64", "NES", "PSX", "SAT", "SMS", "SNES" },
+        unsupportedCores: new[] { "Snes9x" })]
 	public partial class GameShark : Form, IToolForm, IToolFormAutoConfig
 	{
 		#region " Game Genie Dictionary "
diff --git a/BizHawk.Client.EmuHawk/tools/ToolManager.cs b/BizHawk.Client.EmuHawk/tools/ToolManager.cs
index 1a95aba1fe..681ce8ec49 100644
--- a/BizHawk.Client.EmuHawk/tools/ToolManager.cs
+++ b/BizHawk.Client.EmuHawk/tools/ToolManager.cs
@@ -10,6 +10,7 @@ using System.Windows.Forms;
 using BizHawk.Client.Common;
 using BizHawk.Emulation.Common;
 using BizHawk.Common.ReflectionExtensions;
+using BizHawk.Client.EmuHawk.CoreExtensions;
 
 namespace BizHawk.Client.EmuHawk
 {
@@ -743,13 +744,30 @@ namespace BizHawk.Client.EmuHawk
 				.OfType<ToolAttribute>()
 				.FirstOrDefault();
 
-			// If no supported systems mentioned assume all
-			if (attr?.SupportedSystems != null && attr.SupportedSystems.Any())
+            // start with the assumption that if no supported systems are mentioned and no unsupported cores are mentioned
+            // then this is available for all
+            bool supported = true;
+            
+            if (attr?.SupportedSystems != null && attr.SupportedSystems.Any())
 			{
-				return attr.SupportedSystems.Contains(Global.Emulator.SystemId);
-			}
+                // supported systems are available
+                supported = attr.SupportedSystems.Contains(Global.Emulator.SystemId);
 
-			return true;
+                if (supported)
+                {
+                    // check for a core not supported override
+                    if (attr.UnsupportedCores.Contains(Global.Emulator.DisplayName()))
+                        supported = false; 
+                }
+			}
+            else if (attr?.UnsupportedCores != null && attr.UnsupportedCores.Any())
+            {
+                // no supported system specified, but unsupported cores are
+                if (attr.UnsupportedCores.Contains(Global.Emulator.DisplayName()))
+                    supported = false;
+            }
+
+			return supported;
 		}
 
 		// Note: Referencing these properties creates an instance of the tool and persists it.  They should be referenced by type if this is not desired
@@ -973,7 +991,7 @@ namespace BizHawk.Client.EmuHawk
 		public void LoadGameGenieEc()
 		{
 			if (GlobalWin.Tools.IsAvailable<GameShark>())
-			{
+			{                
 				GlobalWin.Tools.Load<GameShark>();
 			}
 		}