diff --git a/py/objtype.c b/py/objtype.c
index cf9311d5c..033765a47 100644
--- a/py/objtype.c
+++ b/py/objtype.c
@@ -334,7 +334,7 @@ mp_obj_t mp_obj_instance_make_new(const mp_obj_type_t *self, size_t n_args, size
     return MP_OBJ_FROM_PTR(o);
 }
 
-const qstr mp_unary_op_method_name[] = {
+const uint16_t mp_unary_op_method_name[] = {
     [MP_UNARY_OP_BOOL] = MP_QSTR___bool__,
     [MP_UNARY_OP_LEN] = MP_QSTR___len__,
     [MP_UNARY_OP_HASH] = MP_QSTR___hash__,
@@ -408,7 +408,7 @@ STATIC mp_obj_t instance_unary_op(mp_unary_op_t op, mp_obj_t self_in) {
     }
 }
 
-const qstr mp_binary_op_method_name[] = {
+const uint16_t mp_binary_op_method_name[] = {
     /*
     MP_BINARY_OP_OR,
     MP_BINARY_OP_XOR,
diff --git a/py/runtime.h b/py/runtime.h
index bbdd7647e..da12f8f04 100644
--- a/py/runtime.h
+++ b/py/runtime.h
@@ -57,9 +57,9 @@ typedef struct _mp_arg_t {
     mp_arg_val_t defval;
 } mp_arg_t;
 
-// defined in objtype.c
-extern const qstr mp_unary_op_method_name[];
-extern const qstr mp_binary_op_method_name[];
+// Tables mapping operator enums to qstrs, defined in objtype.c
+extern const uint16_t mp_unary_op_method_name[];
+extern const uint16_t mp_binary_op_method_name[];
 
 void mp_init(void);
 void mp_deinit(void);