diff --git a/tools/jetpack.lua b/tools/jetpack.lua
index b2d940d..5062a93 100644
--- a/tools/jetpack.lua
+++ b/tools/jetpack.lua
@@ -28,8 +28,10 @@ local function registerJetpack(config)
 			non_combat_torso=1,
 			_industrialtest_jetpack=1
 		}
-		for key,value in pairs(config.groups) do
-			groups[key]=value
+		if config.groups then
+			for key,value in pairs(config.groups) do
+				groups[key]=value
+			end
 		end
 		local definition={
 			description=config.displayName,
@@ -45,8 +47,10 @@ local function registerJetpack(config)
 			_mcl_armor_texture="industrialtest_"..config.name..".png",
 			_industrialtest_tryFly=config.tryFly
 		}
-		for key,value in pairs(config.customKeys) do
-			definition[key]=value
+		if config.customKeys then
+			for key,value in pairs(config.customKeys) do
+				definition[key]=value
+			end
 		end
 		minetest.register_tool("industrialtest:"..config.name,definition)
 	elseif industrialtest.mtgAvailable then