diff --git a/bob/learn/em/kmeans_trainer.cpp b/bob/learn/em/kmeans_trainer.cpp
index fb1fc5fac583e9727964e8e43445b6c9a5e695d8..2fe2c3c2e5202d62f603f0103b73bacb8cb7f826 100644
--- a/bob/learn/em/kmeans_trainer.cpp
+++ b/bob/learn/em/kmeans_trainer.cpp
@@ -484,8 +484,8 @@ static PyObject* PyBobLearnEMKMeansTrainer_reset_accumulators(PyBobLearnEMKMeans
   PyBobLearnEMKMeansMachineObject* kmeans_machine;
   if (!PyArg_ParseTupleAndKeywords(args, kwargs, "O!", kwlist, &PyBobLearnEMKMeansMachine_Type, &kmeans_machine)) return 0;
 
-  bool value = self->cxx->resetAccumulators(*kmeans_machine->cxx);
-  return Py_BuildValue("b", value);
+  self->cxx->resetAccumulators(*kmeans_machine->cxx);
+  Py_RETURN_NONE;
 
   BOB_CATCH_MEMBER("cannot perform the reset_accumulators method", 0)
 }