diff --git a/modules/gfx/pymod/export_primlist.cc b/modules/gfx/pymod/export_primlist.cc
index 8cdaf32303ae80ff65d787642d2e9a01b8d5bc0d..f4c7fddd83fe37909a5b91d9846503768e89da5e 100644
--- a/modules/gfx/pymod/export_primlist.cc
+++ b/modules/gfx/pymod/export_primlist.cc
@@ -52,7 +52,7 @@ namespace {
     float* vp=reinterpret_cast<float*>(PyArray_DATA(va));
     float* np=0;
     float* cp=0;
-    if(ona!=object()) {
+    if(!ona.is_none()) {
       if(!PyArray_Check(ona.ptr())) {
         throw Error("ona is not a numpy array");
       }
@@ -68,7 +68,7 @@ namespace {
       }
       np=reinterpret_cast<float*>(PyArray_DATA(na));
     }
-    if(oca!=object()) {
+    if(!oca.is_none()) {
       if(!PyArray_Check(oca.ptr())) {
         throw Error("oca is not a numpy array");
       }