diff --git a/sim/gate.lua b/sim/gate.lua
index ce8cd29..ae3bcbc 100644
--- a/sim/gate.lua
+++ b/sim/gate.lua
@@ -25,7 +25,7 @@ function Gate.new(objref, definition)
 		objref = objref,
 		definition = definition,
 	}
-	local cdata = ffi.new("char["..(ffi.sizeof("struct Gate") + ffi.sizeof("struct OutPort")*(#gate.ports+1)).."]")
+	local cdata = ffi.new("char["..(ffi.sizeof("struct Gate") + ffi.sizeof("struct OutPort")*(#definition.ports+1)).."]")
 	gate.c = ffi.cast("struct Gate*", cdata)
 	gate.c.in_queue = 0
 	return gate