diff --git a/Patches/StackFirItemsPatch.cs b/Patches/StackFirItemsPatch.cs
index 810feea..f1b8e04 100644
--- a/Patches/StackFirItemsPatch.cs
+++ b/Patches/StackFirItemsPatch.cs
@@ -8,55 +8,93 @@ using System.Reflection;
 
 namespace UIFixes
 {
-    public class StackFirItemsPatch : ModulePatch
+    public static class StackFirItemsPatches
     {
-        private static Type MergeableItemType;
-
-        protected override MethodBase GetTargetMethod()
+        public static void Enable()
         {
-            MethodInfo method = AccessTools.Method(typeof(InteractionsHandlerClass), nameof(InteractionsHandlerClass.smethod_0));
-            MergeableItemType = method.GetParameters()[2].ParameterType.GetElementType(); // parameter is a ref type, get underlying type
-            return method;
+            new ContainerStackPatch().Enable();
+            new TopUpStackPatch().Enable();
         }
 
-        // Reimplementing this entire method to ignore SpawnedInSession for certain types
-        [PatchPrefix]
-        public static bool Prefix(IEnumerable<StashGridClass> gridsToPut, Item itemToMerge, ref object mergeableItem, int overrideCount, ref bool __result)
+        public class ContainerStackPatch : ModulePatch
         {
-            if (!MergeableItemType.IsInstanceOfType(itemToMerge))
+            private static Type MergeableItemType;
+
+            protected override MethodBase GetTargetMethod()
             {
-                mergeableItem = null;
-                __result = false;
+                MethodInfo method = AccessTools.Method(typeof(InteractionsHandlerClass), nameof(InteractionsHandlerClass.smethod_0));
+                MergeableItemType = method.GetParameters()[2].ParameterType.GetElementType(); // parameter is a ref type, get underlying type
+                return method;
             }
 
-            if (overrideCount <= 0)
+            // Reimplementing this entire method to ignore SpawnedInSession for certain types
+            [PatchPrefix]
+            public static bool Prefix(IEnumerable<StashGridClass> gridsToPut, Item itemToMerge, ref object mergeableItem, int overrideCount, ref bool __result)
             {
-                overrideCount = itemToMerge.StackObjectsCount;
+                if (!MergeableItemType.IsInstanceOfType(itemToMerge))
+                {
+                    mergeableItem = null;
+                    __result = false;
+                }
+
+                if (overrideCount <= 0)
+                {
+                    overrideCount = itemToMerge.StackObjectsCount;
+                }
+
+                bool ignoreSpawnedInSession;
+                if (itemToMerge.Template is MoneyClass)
+                {
+                    ignoreSpawnedInSession = Settings.MergeFIRMoney.Value;
+                }
+                else if (itemToMerge.Template is AmmoTemplate)
+                {
+                    ignoreSpawnedInSession = Settings.MergeFIRAmmo.Value;
+                }
+                else
+                {
+                    ignoreSpawnedInSession = Settings.MergeFIROther.Value;
+                }
+
+                mergeableItem = gridsToPut.SelectMany(x => x.Items).Where(x => MergeableItemType.IsInstanceOfType(x))
+                    .Where(x => x != itemToMerge)
+                    .Where(x => x.TemplateId == itemToMerge.TemplateId)
+                    .Where(x => ignoreSpawnedInSession || x.SpawnedInSession == itemToMerge.SpawnedInSession)
+                    .Where(x => x.StackObjectsCount < x.StackMaxSize)
+                    .FirstOrDefault(x => overrideCount <= x.StackMaxSize - x.StackObjectsCount);
+
+                __result = mergeableItem != null;
+                return false;
+            }
+        }
+
+        public class TopUpStackPatch : ModulePatch
+        {
+            protected override MethodBase GetTargetMethod()
+            {
+                return AccessTools.Method(typeof(Item), nameof(Item.IsSameItem));
             }
 
-            bool ignoreSpawnedInSession;
-            if (itemToMerge.Template is MoneyClass)
+            [PatchPrefix]
+            public static bool Prefix(Item __instance, Item other, ref bool __result)
             {
-                ignoreSpawnedInSession = Settings.MergeFIRMoney.Value;
-            }
-            else if (itemToMerge.Template is AmmoTemplate)
-            {
-                ignoreSpawnedInSession = Settings.MergeFIRAmmo.Value;
-            }
-            else
-            {
-                ignoreSpawnedInSession = Settings.MergeFIROther.Value;
-            }
+                bool ignoreSpawnedInSession;
+                if (__instance.Template is MoneyClass)
+                {
+                    ignoreSpawnedInSession = Settings.MergeFIRMoney.Value;
+                }
+                else if (__instance.Template is AmmoTemplate)
+                {
+                    ignoreSpawnedInSession = Settings.MergeFIRAmmo.Value;
+                }
+                else
+                {
+                    ignoreSpawnedInSession = Settings.MergeFIROther.Value;
+                }
 
-            mergeableItem = gridsToPut.SelectMany(x => x.Items).Where(x => MergeableItemType.IsInstanceOfType(x))
-                .Where(x => x != itemToMerge)
-                .Where(x => x.TemplateId == itemToMerge.TemplateId)
-                .Where(x => ignoreSpawnedInSession || x.SpawnedInSession == itemToMerge.SpawnedInSession)
-                .Where(x => x.StackObjectsCount < x.StackMaxSize)
-                .FirstOrDefault(x => overrideCount <= x.StackMaxSize - x.StackObjectsCount);
-
-            __result = mergeableItem != null;
-            return false;
+                __result = __instance.TemplateId == other.TemplateId && __instance.Id != other.Id && (ignoreSpawnedInSession || __instance.SpawnedInSession == other.SpawnedInSession);
+                return false;
+            }
         }
     }
 }
diff --git a/Plugin.cs b/Plugin.cs
index 549e9db..f082f0a 100644
--- a/Plugin.cs
+++ b/Plugin.cs
@@ -24,7 +24,7 @@ namespace UIFixes
             InspectWindowStatsPatches.Enable();
             new RemoveDoorActionsPatch().Enable();
             ScrollPatches.Enable();
-            new StackFirItemsPatch().Enable();
+            StackFirItemsPatches.Enable();
             SwapPatches.Enable();
             SyncScrollPositionPatches.Enable();
             new TransferConfirmPatch().Enable();