diff --git a/src/6502-c++.cpp b/src/6502-c++.cpp
index e668564..74a4ba6 100644
--- a/src/6502-c++.cpp
+++ b/src/6502-c++.cpp
@@ -140,6 +140,8 @@ struct AVR : ASMLine
     sub,
     subi,
     swap,
+
+    tst,
   };
 
   [[nodiscard]] static constexpr OpCode parse_opcode(Type t, std::string_view o)
@@ -196,6 +198,7 @@ struct AVR : ASMLine
       if (o == "inc") { return OpCode::inc; }
       if (o == "nop") { return OpCode::nop; }
       if (o == "jmp") { return OpCode::jmp; }
+      if (o == "tst") { return OpCode::tst; }
     }
     }
     throw std::runtime_error(fmt::format("Unknown opcode: {}", o));
@@ -347,7 +350,14 @@ void translate_instruction(const Personality &personality,
 
   switch (op) {
   case AVR::OpCode::jmp: instructions.emplace_back(mos6502::OpCode::jmp, o1); return;
+  case AVR::OpCode::tst: {
+    // just an lda will set the relevant flags that the tst operation sets, so I think this is
+    // sufficient
+    instructions.emplace_back(mos6502::OpCode::lda, personality.get_register(o1_reg_num));
+    return;
 
+    
+  }
   case AVR::OpCode::dec: instructions.emplace_back(mos6502::OpCode::dec, personality.get_register(o1_reg_num)); return;
   case AVR::OpCode::ldi:
     instructions.emplace_back(mos6502::OpCode::lda, Operand(o2.type, fixup_8bit_literal(o2.value)));