diff --git a/src/Base/QuantityPyImp.cpp b/src/Base/QuantityPyImp.cpp
index 1dfd312aec..46fdfc6596 100644
--- a/src/Base/QuantityPyImp.cpp
+++ b/src/Base/QuantityPyImp.cpp
@@ -83,6 +83,7 @@ int QuantityPy::PyInit(PyObject* args, PyObject* /*kwd*/)
     int i6=0;
     int i7=0;
     int i8=0;
+    PyErr_Clear(); // set by PyArg_ParseTuple()
     if (PyArg_ParseTuple(args, "|diiiiiiii", &f,&i1,&i2,&i3,&i4,&i5,&i6,&i7,&i8)) {
         if (f != DOUBLE_MAX) {
             *self = Quantity(f,Unit(i1,i2,i3,i4,i5,i6,i7,i8));