diff --git a/nw/gui/dochighlight.py b/nw/gui/dochighlight.py
index 4754110d..abf3c122 100644
--- a/nw/gui/dochighlight.py
+++ b/nw/gui/dochighlight.py
@@ -203,9 +203,10 @@ class GuiDocHighlighter(QSyntaxHighlighter):
         # Build a QRegExp for spell checker
         # Include additional characters that the highlighter should
         # consider to be word separators
-        wordSep  = "_+"
+        wordSep  = "_\+"
+        wordSep += nwUnicode.U_ENDASH
         wordSep += nwUnicode.U_EMDASH
-        self.spellRx = QRegularExpression("\\b[^\\s%s]+\\b" % wordSep)
+        self.spellRx = QRegularExpression(r"\b[^\s"+wordSep+r"]+\b")
         self.spellRx.setPatternOptions(QRegularExpression.UseUnicodePropertiesOption)
 
         return True