diff --git a/src/ui/highlighter.h b/src/ui/highlighter.h
--- a/src/ui/highlighter.h
+++ b/src/ui/highlighter.h
@@ -103,6 +103,25 @@
      */
     void setAutomatic(bool automatic);
 
+    /**
+     * Returns whether the automatic language detection is disabled,
+     * overriding the Sonnet settings.
+     *
+     * @return true if the automatic language detection is disabled
+     * @since 5.66
+     */
+    bool autoDetectLanguageDisabled() const;
+
+    /**
+     * Sets whether to disable the automatic language detection.
+     *
+     * @param autoDetectDisabled if true, the language will not be
+     * detected automatically by the spell checker, even if the option
+     * is enabled in the Sonnet settings.
+     * @since 5.66
+     */
+    void setAutoDetectLanguageDisabled(bool autoDetectDisabled);
+
     /**
      * Adds the given word permanently to the dictionary. It will never
      * be marked as misspelled again, even after restarting the application.
diff --git a/src/ui/highlighter.cpp b/src/ui/highlighter.cpp
--- a/src/ui/highlighter.cpp
+++ b/src/ui/highlighter.cpp
@@ -92,6 +92,7 @@
         tokenizer = new WordTokenizer();
         active = true;
         automatic = false;
+        autoDetectLanguageDisabled = false;
         connected = false;
         wordCount = 0;
         errorCount = 0;
@@ -131,6 +132,7 @@
     QPlainTextEdit *plainTextEdit = nullptr;
     bool active;
     bool automatic;
+    bool autoDetectLanguageDisabled;
     bool completeRehighlightRequired;
     bool intraWordEditing;
     bool spellCheckerFound; //cached d->dict->isValid() value
@@ -208,6 +210,11 @@
     return d->automatic;
 }
 
+bool Highlighter::autoDetectLanguageDisabled() const
+{
+    return d->autoDetectLanguageDisabled;
+}
+
 bool Highlighter::intraWordEditing() const
 {
     return d->intraWordEditing;
@@ -230,6 +237,11 @@
     }
 }
 
+void Highlighter::setAutoDetectLanguageDisabled(bool autoDetectDisabled)
+{
+    d->autoDetectLanguageDisabled = autoDetectDisabled;
+}
+
 void Highlighter::slotAutoDetection()
 {
     bool savedActive = d->active;
@@ -339,7 +351,7 @@
         const bool autodetectLanguage = d->spellchecker->testAttribute(Speller::AutoDetectLanguage);
         while (d->languageFilter->hasNext()) {
             QStringRef sentence = d->languageFilter->next();
-            if (autodetectLanguage) {
+            if (autodetectLanguage && !d->autoDetectLanguageDisabled) {
                 QString lang;
                 QPair<int, int> spos = QPair<int, int>(sentence.position(), sentence.length());
                 // try cache first