diff --git a/novelwriter/gui/dochighlight.py b/novelwriter/gui/dochighlight.py
index e24a7904..3b4dc684 100644
--- a/novelwriter/gui/dochighlight.py
+++ b/novelwriter/gui/dochighlight.py
@@ -48,7 +48,7 @@ SPELLRX.setPatternOptions(QRegularExpression.UseUnicodePropertiesOption)
 
 class GuiDocHighlighter(QSyntaxHighlighter):
 
-    __slots__ = ("_tItem", "_tHandle", "_spellCheck", "_hRules", "_hStyles", "_spellErr")
+    __slots__ = ("_tItem", "_tHandle", "_spellCheck", "_spellErr", "_hRules", "_hStyles")
 
     BLOCK_NONE  = 0
     BLOCK_TEXT  = 1