diff --git a/src/lisp/drawl.pla b/src/lisp/drawl.pla
index 2dfb73c..7c1a0f1 100644
--- a/src/lisp/drawl.pla
+++ b/src/lisp/drawl.pla
@@ -721,6 +721,16 @@ def natv_rem(expr)
   return new_int(num[0], num[1])
 end
 
+def natv_neg(expr)
+  var num[2]
+
+  num[0], num[1] = eval_num(expr)
+  load32(@num)
+  neg32
+  store32(@num)
+  return new_int(num[0], num[1])
+end
+
 def natv_gt(expr)
   var num[2]
 
@@ -780,6 +790,7 @@ def install_defaults#0
   new_sym("*")=>natv      = @natv_mul)
   new_sym("/")=>natv      = @natv_div)
   new_sym("REM")=>natv    = @natv_rem)
+  new_sym("NEG")=>natv    = @natv_neg)
   new_sym(">")=>natv      = @natv_gt)
   new_sym("<")=>natv      = @natv_lt)
   new_sym("PRINT")=>natv  = @natv_print)