diff --git a/machines/rotary_macerator.lua b/machines/rotary_macerator.lua
index d0f430d..3ac915c 100644
--- a/machines/rotary_macerator.lua
+++ b/machines/rotary_macerator.lua
@@ -150,10 +150,12 @@ rotaryMacerator.activeOnTimer=function(pos,elapsed,meta,inv)
 	local dstSlot=inv:get_stack("dst",1)
 	local powerAmount=meta:get_int("industrialtest.powerAmount")
 	local rpm=meta:get_int("rpm")
+	local speed=industrialtest.api.getMachineSpeed(meta)
+	local requiredPower=elapsed*rotaryMacerator.opPower*speed
 
 	industrialtest.internal.chargeFromPowerStorageItem(meta,inv)
 
-	if srcSlot:is_empty() or powerAmount<rotaryMacerator.opPower then
+	if srcSlot:is_empty() or powerAmount<requiredPower then
 		meta:set_float("srcTime",0)
 		meta:set_float("maxSrcTime",0)
 		minetest.swap_node(pos,{
@@ -189,16 +191,13 @@ rotaryMacerator.activeOnTimer=function(pos,elapsed,meta,inv)
 
 	local srcTime=meta:get_float("srcTime")+elapsed*(1+rpm/7500)
 	if srcTime>=meta:get_float("maxSrcTime") then
-		local speed=industrialtest.api.getMachineSpeed(meta)
-		local multiplier=1
-		if srcSlot:get_count()>=speed then
-			multiplier=speed
-		end
+		local multiplier=math.min(srcSlot:get_count(),speed)
+		local prevCount=resultStack:get_count()
 		resultStack:set_count(resultStack:get_count()*multiplier)
-		inv:add_item("dst",resultStack)
+		local leftover=inv:add_item("dst",resultStack)
 		meta:set_float("srcTime",0)
 		meta:set_float("maxSrcTime",0)
-		srcSlot:set_count(srcSlot:get_count()-multiplier)
+		srcSlot:take_item(multiplier-leftover:get_count()/prevCount)
 		inv:set_stack("src",1,srcSlot)
 		meta:set_int("rpm",math.min(rpm+750*elapsed,7500))
 		if modified then
@@ -225,6 +224,8 @@ rotaryMacerator.activeOnTimer=function(pos,elapsed,meta,inv)
 		meta:set_float("srcTime",srcTime)
 	end
 
+	industrialtest.api.addPower(meta,-requiredPower)
+
 	return true,true
 end