diff --git a/py/stream.c b/py/stream.c
index 98f62518a5..2b4410728f 100644
--- a/py/stream.c
+++ b/py/stream.c
@@ -98,18 +98,15 @@ STATIC mp_obj_t stream_read(uint n_args, const mp_obj_t *args) {
     }
 }
 
-STATIC mp_obj_t stream_write(mp_obj_t self_in, mp_obj_t arg) {
+mp_obj_t mp_stream_write(mp_obj_t self_in, const void *buf, mp_uint_t len) {
     struct _mp_obj_base_t *o = (struct _mp_obj_base_t *)self_in;
     if (o->type->stream_p == NULL || o->type->stream_p->write == NULL) {
         // CPython: io.UnsupportedOperation, OSError subclass
         nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, "Operation not supported"));
     }
 
-    mp_buffer_info_t bufinfo;
-    mp_get_buffer_raise(arg, &bufinfo, MP_BUFFER_READ);
-
     int error;
-    mp_int_t out_sz = o->type->stream_p->write(self_in, bufinfo.buf, bufinfo.len, &error);
+    mp_int_t out_sz = o->type->stream_p->write(self_in, buf, len, &error);
     if (out_sz == -1) {
         if (is_nonblocking_error(error)) {
             // http://docs.python.org/3/library/io.html#io.RawIOBase.write
@@ -125,6 +122,12 @@ STATIC mp_obj_t stream_write(mp_obj_t self_in, mp_obj_t arg) {
     }
 }
 
+STATIC mp_obj_t stream_write_method(mp_obj_t self_in, mp_obj_t arg) {
+    mp_buffer_info_t bufinfo;
+    mp_get_buffer_raise(arg, &bufinfo, MP_BUFFER_READ);
+    return mp_stream_write(self_in, bufinfo.buf, bufinfo.len);
+}
+
 STATIC mp_obj_t stream_readall(mp_obj_t self_in) {
     struct _mp_obj_base_t *o = (struct _mp_obj_base_t *)self_in;
     if (o->type->stream_p == NULL || o->type->stream_p->read == NULL) {
@@ -248,4 +251,4 @@ mp_obj_t mp_stream_unbuffered_iter(mp_obj_t self) {
 MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mp_stream_read_obj, 1, 2, stream_read);
 MP_DEFINE_CONST_FUN_OBJ_1(mp_stream_readall_obj, stream_readall);
 MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mp_stream_unbuffered_readline_obj, 1, 2, stream_unbuffered_readline);
-MP_DEFINE_CONST_FUN_OBJ_2(mp_stream_write_obj, stream_write);
+MP_DEFINE_CONST_FUN_OBJ_2(mp_stream_write_obj, stream_write_method);
diff --git a/py/stream.h b/py/stream.h
index e52508daae..4cdc1b4dc5 100644
--- a/py/stream.h
+++ b/py/stream.h
@@ -32,3 +32,5 @@ MP_DECLARE_CONST_FUN_OBJ(mp_stream_write_obj);
 
 // Iterator which uses mp_stream_unbuffered_readline_obj
 mp_obj_t mp_stream_unbuffered_iter(mp_obj_t self);
+
+mp_obj_t mp_stream_write(mp_obj_t self_in, const void *buf, mp_uint_t len);