diff --git a/src/pocketpy.cpp b/src/pocketpy.cpp
index 73ddd61f..37284b63 100644
--- a/src/pocketpy.cpp
+++ b/src/pocketpy.cpp
@@ -444,8 +444,8 @@ void init_builtins(VM* _vm) {
         return VAR(_CAST(i64, _0) % rhs);
     });
 
-    _vm->bind(_vm->_t(VM::tp_int), "bit_length(self)", [](VM* vm, ArgsView args) {
-        i64 x = CAST(i64, args[0]);
+    _vm->bind_method<0>(VM::tp_int, "bit_length", [](VM* vm, ArgsView args) {
+        i64 x = _CAST(i64, args[0]);
         if(x < 0) x = -x;
         int bits = 0;
         while(x){ x >>= 1; bits++; }
@@ -1633,4 +1633,4 @@ CodeObject_ VM::compile(std::string_view source, const Str& filename, CompileMod
     }
 }
 
-}   // namespace pkpy
\ No newline at end of file
+}   // namespace pkpy