diff --git a/bson/_cbsonmodule.c b/bson/_cbsonmodule.c
index e606809ba..ed0179fa1 100644
--- a/bson/_cbsonmodule.c
+++ b/bson/_cbsonmodule.c
@@ -1485,6 +1485,9 @@ int write_dict(PyObject* self, buffer_t buffer,
         Py_DECREF(value);
     }
     Py_DECREF(iter);
+    if (PyErr_Occurred()) {
+        return 0;
+    }
 
     /* write null byte and fill in length */
     if (!buffer_write_bytes(buffer, &zero, 1)) {