diff --git a/src/mir/Lowering.cpp b/src/mir/Lowering.cpp
index 0af6d93..f85fc44 100644
--- a/src/mir/Lowering.cpp
+++ b/src/mir/Lowering.cpp
@@ -871,6 +871,11 @@ void LowerInstruction(const ir::Instruction& inst, MachineFunction& function,
       }
       return;
     }
+
+    // Br 和 CondBr 在 LowerModule 中已处理，不应到达这里
+    case ir::Opcode::Br:
+    case ir::Opcode::CondBr:
+      return;
   }
 
   throw std::runtime_error(FormatError("mir", "暂不支持该 IR 指令"));