diff --git a/arch/zx48k/optimizer/basicblock.py b/arch/zx48k/optimizer/basicblock.py
index beb990564..81a3aa1a7 100644
--- a/arch/zx48k/optimizer/basicblock.py
+++ b/arch/zx48k/optimizer/basicblock.py
@@ -330,7 +330,7 @@ def update_goes_and_comes(self):
             bb = stack.pop(0)
             while True:
                 if bb is None:
-                    DummyBasicBlock(ALL_REGS, ALL_REGS)
+                    bb = DummyBasicBlock(ALL_REGS, ALL_REGS)
 
                 if bb in bbset:
                     break