diff --git a/src/main/scala/millfork/compiler/z80/ZBuiltIns.scala b/src/main/scala/millfork/compiler/z80/ZBuiltIns.scala
index b344b404..08faa034 100644
--- a/src/main/scala/millfork/compiler/z80/ZBuiltIns.scala
+++ b/src/main/scala/millfork/compiler/z80/ZBuiltIns.scala
@@ -401,7 +401,7 @@ object ZBuiltIns {
               setup ++ List(
                 ZLine.implied(CPL),
                 ZLine.register(INC, ZRegister.A),
-                ZLine.register(SUB, lv),
+                ZLine.register(ADD, lv),
                 ZLine.ld8(lv, ZRegister.A))
             }
         }