diff --git a/src/wrapping_dap_chain_common.c b/src/wrapping_dap_chain_common.c
index 9bb16e5d4ff20de9b1d9531a677f5e24e517f541..b6984985f3c9dee8c61e2456a1a2cc4d92ef32b0 100644
--- a/src/wrapping_dap_chain_common.c
+++ b/src/wrapping_dap_chain_common.c
@@ -34,6 +34,7 @@ PyObject *dap_chain_addr_fill_py(PyObject *self, PyObject *args){
     if (!PyArg_ParseTuple(args, "O|O", &key, &net_id))
         return NULL;
     dap_chain_addr_fill(((PyDapChainAddrObject*)self)->addr, ((PyCryptoKeyObject*)key)->key, &(((PyDapChainNetIdObject*)net_id)->net_id));
+    return self;
 }
 
 PyObject *dap_chain_addr_check_sum_py(PyObject *self, PyObject *args){
diff --git a/src/wrapping_dap_chain_datum_tx.c b/src/wrapping_dap_chain_datum_tx.c
index dc1c32df5fd525c9a0ad3c94d7a2d7af4d48bf87..5ed4299e3194fea347357304ff3daa429931d828 100644
--- a/src/wrapping_dap_chain_datum_tx.c
+++ b/src/wrapping_dap_chain_datum_tx.c
@@ -168,7 +168,7 @@ static dap_chain_datum_tx_t **PyListToDapChainDatumTxArray(PyObject *a_in_obj){
 }
 
 static PyObject* DapChainDatumTxArrayToPyList(dap_chain_datum_tx_t** datum_txs){
-    size_t len = sizeof(datum_txs) / sizeof(datum_txs[0]);
+    size_t len = sizeof(datum_txs) / sizeof(*datum_txs);
     PyObject* list = PyList_New((Py_ssize_t)len);
     for (size_t i=0; i < len; i++){
         PyObject *obj = _PyObject_New(&DapChainDatumTx_DapChainDatumTxObjectType);
@@ -188,7 +188,7 @@ dap_chain_tx_out_cond_t **PyListToDapChainTxOutCond(PyObject *list){
 }
 
 PyObject *DapChainTxOutCondObjectToPyList(dap_chain_tx_out_cond_t **out_cond){
-    size_t len = sizeof(out_cond) / sizeof(out_cond[0]);
+    size_t len = sizeof(out_cond) / sizeof(*out_cond);
     PyObject *list = PyList_New((Py_ssize_t)len);
     for (size_t i=0; i< len;i++ ){
         PyObject *obj = _PyObject_New(&DapChainTxOutCond_DapChainTxOutCondObjectType);