diff --git a/api/common.lua b/api/common.lua
index 8b01966..8342e39 100644
--- a/api/common.lua
+++ b/api/common.lua
@@ -41,6 +41,15 @@ function industrialtest.internal.clamp(num,min,max)
 	return math.max(math.min(num,max),min)
 end
 
+function industrialtest.internal.addYVelocityClamped(player,vel,max)
+	local playerVel=player:get_velocity()
+	if playerVel.y+vel>max then
+		player:add_velocity(vector.new(0,math.max(max-playerVel.y,0),0))
+	else
+		player:add_velocity(vector.new(0,vel,0))
+	end
+end
+
 function industrialtest.internal.unpackTableInto(first,second)
 	for k,v in pairs(second) do
 		first[k]=v
diff --git a/tools/jetpack.lua b/tools/jetpack.lua
index 2c84a00..46b51fc 100644
--- a/tools/jetpack.lua
+++ b/tools/jetpack.lua
@@ -25,7 +25,7 @@ function industrialtest.JetpackBase.update(self, player, inv, itemstack, dtime)
 	local playerName = player:get_player_name()
 	local control = player:get_player_control()
 	if control.jump and self:tryFly(itemstack) then
-		self.addYVelocityClamped(player,1,10)
+		industrialtest.internal.addYVelocityClamped(player,1,10)
 		if not soundHandles[playerName] then
 			local pos = player:get_pos()
 			local handle = minetest.sound_play("industrialtest_jetpack_loop", {
@@ -47,15 +47,6 @@ function industrialtest.JetpackBase.update(self, player, inv, itemstack, dtime)
 	return false
 end
 
-function industrialtest.JetpackBase.addYVelocityClamped(player,vel,max)
-	local playerVel=player:get_velocity()
-	if playerVel.y+vel>max then
-		player:add_velocity(vector.new(0,math.max(max-playerVel.y,0),0))
-	else
-		player:add_velocity(vector.new(0,vel,0))
-	end
-end
-
 industrialtest.Jetpack=table.copy(industrialtest.JetpackBase)
 industrialtest.internal.unpackTableInto(industrialtest.Jetpack,{
 	-- _v is hack to suppress "Registered armor doesn't have material at the end of registration name" warning from 3D Armor.
diff --git a/tools/quantum_suit.lua b/tools/quantum_suit.lua
index 1f26078..0ca5e56 100644
--- a/tools/quantum_suit.lua
+++ b/tools/quantum_suit.lua
@@ -87,7 +87,7 @@ industrialtest.internal.unpackTableInto(industrialtest.QuantumBodyarmor,{
 	part="torso",
 	modelImage="industrialtest_quantum_bodyarmor.png",
 	update=industrialtest.JetpackBase.update,
-	addYVelocityClamped=industrialtest.JetpackBase.addYVelocityClamped,
+	addYVelocityClamped=industrialtest.internal.addYVelocityClamped,
 	tryFly=industrialtest.ElectricJetpack.tryFly
 })