diff --git a/Modules/_zoneinfo.c b/Modules/_zoneinfo.c
index e2ab04cc2073c5..f1961be0d3f8b9 100644
--- a/Modules/_zoneinfo.c
+++ b/Modules/_zoneinfo.c
@@ -272,6 +272,7 @@ zoneinfo_new_instance(zoneinfo_state *state, PyTypeObject *type, PyObject *key)
 
     goto cleanup;
 error:
+    assert(PyErr_Occurred());
     Py_CLEAR(self);
 cleanup:
     if (file_obj != NULL) {
@@ -458,6 +459,7 @@ zoneinfo_ZoneInfo_from_file_impl(PyTypeObject *type, PyTypeObject *cls,
     return (PyObject *)self;
 
 error:
+    assert(PyErr_Occurred());
     Py_XDECREF(file_repr);
     Py_XDECREF(self);
     return NULL;
@@ -1043,10 +1045,12 @@ load_data(zoneinfo_state *state, PyZoneInfo_ZoneInfo *self, PyObject *file_obj)
     self->trans_list_utc =
         PyMem_Malloc(self->num_transitions * sizeof(int64_t));
     if (self->trans_list_utc == NULL) {
+        PyErr_NoMemory();
         goto error;
     }
     trans_idx = PyMem_Malloc(self->num_transitions * sizeof(Py_ssize_t));
     if (trans_idx == NULL) {
+        PyErr_NoMemory();
         goto error;
     }
 
@@ -1086,6 +1090,7 @@ load_data(zoneinfo_state *state, PyZoneInfo_ZoneInfo *self, PyObject *file_obj)
     isdst = PyMem_Malloc(self->num_ttinfos * sizeof(unsigned char));
 
     if (utcoff == NULL || isdst == NULL) {
+        PyErr_NoMemory();
         goto error;
     }
     for (size_t i = 0; i < self->num_ttinfos; ++i) {
@@ -1115,6 +1120,7 @@ load_data(zoneinfo_state *state, PyZoneInfo_ZoneInfo *self, PyObject *file_obj)
 
     dstoff = PyMem_Calloc(self->num_ttinfos, sizeof(long));
     if (dstoff == NULL) {
+        PyErr_NoMemory();
         goto error;
     }
 
@@ -1131,6 +1137,7 @@ load_data(zoneinfo_state *state, PyZoneInfo_ZoneInfo *self, PyObject *file_obj)
     // Build _ttinfo objects from utcoff, dstoff and abbr
     self->_ttinfos = PyMem_Malloc(self->num_ttinfos * sizeof(_ttinfo));
     if (self->_ttinfos == NULL) {
+        PyErr_NoMemory();
         goto error;
     }
     for (size_t i = 0; i < self->num_ttinfos; ++i) {
@@ -1151,6 +1158,7 @@ load_data(zoneinfo_state *state, PyZoneInfo_ZoneInfo *self, PyObject *file_obj)
     self->trans_ttinfos =
         PyMem_Calloc(self->num_transitions, sizeof(_ttinfo *));
     if (self->trans_ttinfos == NULL) {
+        PyErr_NoMemory();
         goto error;
     }
     for (size_t i = 0; i < self->num_transitions; ++i) {
@@ -2135,6 +2143,7 @@ ts_to_local(size_t *trans_idx, int64_t *trans_utc, long *utcoff,
     for (size_t i = 0; i < 2; ++i) {
         trans_local[i] = PyMem_Malloc(num_transitions * sizeof(int64_t));
         if (trans_local[i] == NULL) {
+            PyErr_NoMemory();
             return -1;
         }