diff --git a/src/nrnpython/nrnpy_p2h.cpp b/src/nrnpython/nrnpy_p2h.cpp
index 4cf0f5dba8..c9ac0b10d9 100644
--- a/src/nrnpython/nrnpy_p2h.cpp
+++ b/src/nrnpython/nrnpy_p2h.cpp
@@ -687,9 +687,9 @@ static PyObject* char2pylist(char* buf, int np, int* cnt, int* displ) {
 }
 
 #if NRNMPI
-static PyObject* py_allgather(PyObject* psrc) {
+static nb::object py_allgather(nb::handle psrc) {
     int np = nrnmpi_numprocs;
-    auto sbuf = pickle(psrc);
+    auto sbuf = pickle(psrc.ptr());
     // what are the counts from each rank
     int* rcnt = new int[np];
     rcnt[nrnmpi_myid] = static_cast<int>(sbuf.size());
@@ -699,16 +699,16 @@ static PyObject* py_allgather(PyObject* psrc) {
 
     nrnmpi_char_allgatherv(sbuf.data(), rbuf, rcnt, rdispl);
 
-    PyObject* pdest = char2pylist(rbuf, np, rcnt, rdispl);
+    nb::object pdest = nb::steal(char2pylist(rbuf, np, rcnt, rdispl));
     delete[] rbuf;
     delete[] rcnt;
     delete[] rdispl;
     return pdest;
 }
 
-static PyObject* py_gather(PyObject* psrc, int root) {
+static nb::object py_gather(nb::handle psrc, int root) {
     int np = nrnmpi_numprocs;
-    auto sbuf = pickle(psrc);
+    auto sbuf = pickle(psrc.ptr());
     // what are the counts from each rank
     int scnt = static_cast<int>(sbuf.size());
     int* rcnt = NULL;
@@ -725,24 +725,22 @@ static PyObject* py_gather(PyObject* psrc, int root) {
 
     nrnmpi_char_gatherv(sbuf.data(), scnt, rbuf, rcnt, rdispl, root);
 
-    PyObject* pdest = Py_None;
+    nb::object pdest = nb::none();
     if (root == nrnmpi_myid) {
-        pdest = char2pylist(rbuf, np, rcnt, rdispl);
+        pdest = std::steal(char2pylist(rbuf, np, rcnt, rdispl));
         delete[] rbuf;
         delete[] rcnt;
         delete[] rdispl;
-    } else {
-        Py_INCREF(pdest);
     }
     return pdest;
 }
 
-static PyObject* py_broadcast(PyObject* psrc, int root) {
+static nb::object py_broadcast(nb::handle psrc, int root) {
     // Note: root returns reffed psrc.
     std::vector<char> buf{};
     int cnt = 0;
     if (root == nrnmpi_myid) {
-        buf = pickle(psrc);
+        buf = pickle(psrc.ptr());
         cnt = static_cast<int>(buf.size());
     }
     nrnmpi_int_broadcast(&cnt, 1, root);
@@ -750,12 +748,9 @@ static PyObject* py_broadcast(PyObject* psrc, int root) {
         buf.resize(cnt);
     }
     nrnmpi_char_broadcast(buf.data(), cnt, root);
-    PyObject* pdest = psrc;
+    nb::object pdest = psrc;
     if (root != nrnmpi_myid) {
-        nb::object po = unpickle(buf);
-        pdest = po.release().ptr();
-    } else {
-        Py_INCREF(pdest);
+        pdest = unpickle(buf);
     }
     return pdest;
 }
@@ -820,16 +815,16 @@ static Object* py_alltoall_type(int size, int type) {
     nb::object pdest;
 
     if (type == 2) {
-        pdest = nb::steal(py_allgather(psrc.ptr()));
+        pdest = py_allgather(psrc);
     } else if (type != 1 && type != 5) {
         root = size;
         if (root < 0 || root >= np) {
             hoc_execerror("root rank must be >= 0 and < nhost", 0);
         }
         if (type == 3) {
-            pdest = nb::steal(py_gather(psrc.ptr(), root));
+            pdest = py_gather(psrc, root);
         } else if (type == 4) {
-            pdest = nb::steal(py_broadcast(psrc.ptr(), root));
+            pdest = py_broadcast(psrc, root);
         }
     } else {
         if (type == 5) {  // scatter