diff --git a/boa/precompile.py b/boa/precompile.py
index 9ebaea87..bf940fba 100644
--- a/boa/precompile.py
+++ b/boa/precompile.py
@@ -66,7 +66,7 @@ def decorator(func):
         vy_ast = parse_to_ast(user_signature + ": view").body[0]
         func_t = ContractFunctionT.from_FunctionDef(vy_ast, is_interface=True)
 
-        args_t = TupleT(tuple(func_t.arguments.values()))
+        args_t = TupleT(tuple(func_t.argument_types))
 
         def wrapper(computation):
             # Decode input arguments from message data
@@ -92,7 +92,7 @@ def wrapper(computation):
         address = keccak256(user_signature.encode("utf-8"))[:20]
         register_raw_precompile(address, wrapper, force=force)
 
-        args = list(func_t.arguments.items())
+        args = [(arg.name, arg.typ) for arg in func_t.arguments]
         fn_name = func_t.name
         builtin = PrecompileBuiltin(fn_name, args, func_t.return_type, address)