diff --git a/calibre-plugin/dialogs.py b/calibre-plugin/dialogs.py
index 7bf93a77..233cd688 100644
--- a/calibre-plugin/dialogs.py
+++ b/calibre-plugin/dialogs.py
@@ -1532,7 +1532,8 @@ class ViewLog(SizePersistedDialog):
                 error_msg=error_msg[:200]+" ..."
             label = QLabel('%s: %s'%(lineno, error_msg))
             label.setWordWrap(True)
-            if QApplication.instance().is_dark_theme:
+            if( hasattr(QApplication.instance(),'is_dark_theme')
+                and QApplication.instance().is_dark_theme ):
                 label.setStyleSheet("QLabel { margin-left: 2em; color : aqua; } QLabel:hover { color: red; }");
             else:
                 label.setStyleSheet("QLabel { margin-left: 2em; color : blue; } QLabel:hover { color: red; }");
diff --git a/calibre-plugin/inihighlighter.py b/calibre-plugin/inihighlighter.py
index f2f21b05..d00e21a6 100644
--- a/calibre-plugin/inihighlighter.py
+++ b/calibre-plugin/inihighlighter.py
@@ -42,7 +42,8 @@ class IniHighlighter(QSyntaxHighlighter):
             'comments':Qt.darkYellow
             }
         try:
-            if QApplication.instance().is_dark_theme:
+            if( hasattr(QApplication.instance(),'is_dark_theme')
+                and QApplication.instance().is_dark_theme ):
                 colors = {
                     'knownentries':Qt.green,
                     'errors':Qt.red,