diff --git a/vm/ophandler.go b/vm/ophandler.go
index 2959259..d58055f 100644
--- a/vm/ophandler.go
+++ b/vm/ophandler.go
@@ -81,7 +81,7 @@ func (state *State) handleDivideSigned(instr *Instruction) {
 
 func (state *State) handleNot(instr *Instruction) {
 	in := state.readUnsigned(&instr.Operand1)
-	state.writeUnsigned(&instr.Operand1, in^uint64(0xffffffffffffffff))
+	state.writeUnsigned(&instr.Operand1, ^in)
 }
 
 func (state *State) handleAnd(instr *Instruction) {