diff --git a/gen_input/templates/interp/CORENAME.cpp.gtl b/gen_input/templates/interp/CORENAME.cpp.gtl
index 4b84520..ebedab0 100644
--- a/gen_input/templates/interp/CORENAME.cpp.gtl
+++ b/gen_input/templates/interp/CORENAME.cpp.gtl
@@ -92,7 +92,7 @@ protected:
     using compile_ret_t = virt_addr_t;
     using compile_func = compile_ret_t (this_class::*)(virt_addr_t &pc, code_word_t instr);
 
-    inline const char *name(size_t index){return traits::reg_aliases.at(index);}
+    inline const char *name(size_t index){return index<traits::reg_aliases.size()?traits::reg_aliases[index]:"illegal";}
 
     typename arch::traits<ARCH>::opcode_e decode_inst_id(code_word_t instr);
     virt_addr_t execute_inst(finish_cond_e cond, virt_addr_t start, uint64_t icount_limit) override;