diff --git a/src/Modules/CalcPerform.lua b/src/Modules/CalcPerform.lua
index eb0b3e18dc..b2f044f345 100644
--- a/src/Modules/CalcPerform.lua
+++ b/src/Modules/CalcPerform.lua
@@ -1707,7 +1707,20 @@ function calcs.perform(env, skipEHP)
 		local flaskBuffsNonPlayer = {}
 		local flaskBuffsPerBaseNonPlayer = {}
 
+		local slotIndex = env.itemSlotIndex or { }
+		local orderedFlasks = { }
 		for item in pairs(flasks) do
+			t_insert(orderedFlasks, item)
+		end
+		table.sort(orderedFlasks, function(a, b)
+			local posA = slotIndex[a] or 0
+			local posB = slotIndex[b] or 0
+			if posA ~= posB then
+				return posA < posB
+			end
+			return (a.id or 0) < (b.id or 0)
+		end)
+		for _, item in ipairs(orderedFlasks) do
 			flaskBuffsPerBase[item.baseName] = flaskBuffsPerBase[item.baseName] or {}
 			flaskBuffsPerBaseNonPlayer[item.baseName] = flaskBuffsPerBaseNonPlayer[item.baseName] or {}
 			flaskConditions["UsingFlask"] = true
@@ -1810,7 +1823,20 @@ function calcs.perform(env, skipEHP)
 		local charmConditions = {}
 		local charmBuffsPerBase = {}
 
+		local slotIndex = env.itemSlotIndex or { }
+		local orderedCharms = { }
 		for item in pairs(charms) do
+			t_insert(orderedCharms, item)
+		end
+		table.sort(orderedCharms, function(a, b)
+			local posA = slotIndex[a] or 0
+			local posB = slotIndex[b] or 0
+			if posA ~= posB then
+				return posA < posB
+			end
+			return (a.id or 0) < (b.id or 0)
+		end)
+		for _, item in ipairs(orderedCharms) do
 			if charmLimit <= 0 then
 				break
 			end
diff --git a/src/Modules/CalcSetup.lua b/src/Modules/CalcSetup.lua
index 2922ef02f6..164e2d71ff 100644
--- a/src/Modules/CalcSetup.lua
+++ b/src/Modules/CalcSetup.lua
@@ -1267,10 +1267,20 @@ function calcs.initEnv(build, mode, override, specEnv)
 			end
 		end
 
+		env.itemSlotIndex = { }
 		for _, slot in pairs(build.itemsTab.orderedSlots) do
 			local slotName = slot.slotName
 			local item = items[slotName]
 			local node = slot.nodeId and env.spec.nodes[slot.nodeId]
+			if item then
+				local slotIndex = tonumber(slotName:match("%d+")) or 0
+				-- Repeated flasks/charms keep their earliest active slot.
+				if not (env.flasks[item] or env.charms[item]) then
+					env.itemSlotIndex[item] = slotIndex
+				elseif slot.active then
+					env.itemSlotIndex[item] = m_min(env.itemSlotIndex[item], slotIndex)
+				end
+			end
 			if item and item.type == "Flask" then
 				if slot.active then
 					env.flasks[item] = true