diff --git a/src/python/_rpitxmodule.c b/src/python/_rpitxmodule.c
index d2d559f..c946587 100644
--- a/src/python/_rpitxmodule.c
+++ b/src/python/_rpitxmodule.c
@@ -103,16 +103,16 @@ static void reset(void) {
 
 static PyObject*
 _rpitx_broadcast_fm(PyObject* self, PyObject* args) {
-	int address;
-	int length;
+	long int address;
 	float frequency;
-	if (!PyArg_ParseTuple(args, "iif", &address, &length, &frequency)) {
+
+	assert(sizeof(address) == sizeof(sampleBase));
+	if (!PyArg_ParseTuple(args, "lif", &address, &sampleLength, &frequency)) {
 		PyErr_SetString(rpitxError, "Invalid arguments");
 		Py_RETURN_NONE;
 	}
 
-	sampleBase = (void*)address;
-	sampleLength = length;
+	sampleBase = ((void*)address);
 	sampleOffset = 0;
 
 	SF_VIRTUAL_IO virtualIo = {
diff --git a/src/python/rpitx/_hidden.py b/src/python/rpitx/_hidden.py
index 0c1a43d..d2b81bb 100644
--- a/src/python/rpitx/_hidden.py
+++ b/src/python/rpitx/_hidden.py
@@ -40,4 +40,4 @@ def broadcast_fm(file_, frequency):
     raw_array = array.array('c')
     raw_array.fromstring(wav_data.getvalue())
     array_address, length = raw_array.buffer_info()
-    _rpitx.broadcast_fm(array_address, length, frequency)
+    _rpitx.broadcast_fm(long(array_address), length, frequency)