diff --git a/apps/ivr/IvrDialogBase.cpp b/apps/ivr/IvrDialogBase.cpp
index e7b2d77d..ad715a9e 100644
--- a/apps/ivr/IvrDialogBase.cpp
+++ b/apps/ivr/IvrDialogBase.cpp
@@ -36,7 +36,7 @@ static PyObject* IvrDialogBase_new(PyTypeObject *type, PyObject *args, PyObject
       return NULL;
     }
     
-    if (!PyCObject_Check(o_dlg)){
+    if ((NULL == o_dlg) || !PyCObject_Check(o_dlg)){
 	    
       Py_DECREF(self);
       return NULL;
diff --git a/apps/ivr/IvrSipDialog.cpp b/apps/ivr/IvrSipDialog.cpp
index 59093099..5485cd4d 100644
--- a/apps/ivr/IvrSipDialog.cpp
+++ b/apps/ivr/IvrSipDialog.cpp
@@ -26,7 +26,7 @@ static PyObject* IvrSipDialog_new(PyTypeObject *type, PyObject *args, PyObject *
       return NULL;
     }
     
-    if (!PyCObject_Check(o_dlg)){
+    if ((NULL == o_dlg) || !PyCObject_Check(o_dlg)){
 	    
       Py_DECREF(self);
       return NULL;
diff --git a/apps/ivr/IvrSipReply.cpp b/apps/ivr/IvrSipReply.cpp
index 0b60be20..684ec0a7 100644
--- a/apps/ivr/IvrSipReply.cpp
+++ b/apps/ivr/IvrSipReply.cpp
@@ -48,7 +48,7 @@ static PyObject* IvrSipReply_new(PyTypeObject *type, PyObject *args, PyObject *k
       return NULL;
     }
     
-    if (!PyCObject_Check(o_req)){
+    if ((NULL == o_req) || !PyCObject_Check(o_req)){
 	    
       Py_DECREF(self);
       return NULL;
diff --git a/apps/ivr/IvrSipRequest.cpp b/apps/ivr/IvrSipRequest.cpp
index dc724554..03da2fe0 100644
--- a/apps/ivr/IvrSipRequest.cpp
+++ b/apps/ivr/IvrSipRequest.cpp
@@ -49,7 +49,7 @@ static PyObject* IvrSipRequest_new(PyTypeObject *type, PyObject *args, PyObject
       return NULL;
     }
     
-    if (!PyCObject_Check(o_req)){
+    if ((NULL == o_req) || !PyCObject_Check(o_req)){
 	    
       Py_DECREF(self);
       return NULL;