diff --git a/src/ioncmodule.c b/src/ioncmodule.c
index b53258d..747d6f9 100644
--- a/src/ioncmodule.c
+++ b/src/ioncmodule.c
@@ -315,8 +315,13 @@ static iERR ionc_write_annotations(hWRITER writer, PyObject* obj) {
         SUCCEED();
     }
 
-    annotations = PySequence_Fast(annotations, "expected sequence");
-    Py_ssize_t len = PySequence_Size(annotations);
+    PyObject* annotations_seq = PySequence_Fast(annotations, "expected sequence");
+    Py_DECREF(annotations);
+    annotations = annotations_seq;
+    if (annotations == NULL) {
+        _FAILWITH_PENDING_PYERR();
+    }
+    Py_ssize_t len = PySequence_Fast_GET_SIZE(annotations);
     Py_ssize_t i;
 
     for (i = 0; i < len; i++) {
@@ -333,7 +338,6 @@ static iERR ionc_write_annotations(hWRITER writer, PyObject* obj) {
         Py_DECREF(pyAnnotation);
         if (err) break;
     }
-    Py_XDECREF(annotations);
 fail:
     Py_XDECREF(annotations);
     cRETURN;