diff --git a/src/nvlib/exporter/nv_doc_exporter.py b/src/nvlib/exporter/nv_doc_exporter.py
index 11057b0..5037233 100644
--- a/src/nvlib/exporter/nv_doc_exporter.py
+++ b/src/nvlib/exporter/nv_doc_exporter.py
@@ -97,6 +97,7 @@ def run(self, source, suffix, **kwargs):
                     defaultButton = 0
             except:
                 timeStatus = ''
+                defaultButton = 0
             self._targetFileDate = datetime.fromtimestamp(targetTimestamp).strftime('%c')
             title = _('Export document')
             message = _('{0} already exists.\n(last saved on {2})\n{1}.\n\nOpen this document instead of overwriting it?').format(