diff --git a/src/plugins/diffeditor/diffeditor.cpp b/src/plugins/diffeditor/diffeditor.cpp
index 92164f435de..085b5b05593 100644
--- a/src/plugins/diffeditor/diffeditor.cpp
+++ b/src/plugins/diffeditor/diffeditor.cpp
@@ -147,7 +147,6 @@ private:
     void documentHasChanged();
     void toggleDescription();
     void updateDescription();
-    void updateDescriptionHighlighter();
     void contextLineCountHasChanged(int lines);
     void ignoreWhitespaceHasChanged();
     void prepareForReload();
@@ -300,8 +299,6 @@ void DiffEditor::setDocument(std::shared_ptr<DiffEditorDocument> doc)
             this, &DiffEditor::documentHasChanged);
     connect(m_document.get(), &DiffEditorDocument::descriptionChanged,
             this, &DiffEditor::updateDescription);
-    connect(m_document.get(), &DiffEditorDocument::descriptionHighlighterChanged,
-            this, &DiffEditor::updateDescriptionHighlighter);
     connect(m_document.get(), &DiffEditorDocument::aboutToReload,
             this, &DiffEditor::prepareForReload);
     connect(m_document.get(), &DiffEditorDocument::reloadFinished,
@@ -459,13 +456,6 @@ void DiffEditor::updateDescription()
     m_toggleDescriptionAction->setVisible(!description.isEmpty());
 }
 
-void DiffEditor::updateDescriptionHighlighter()
-{
-    const auto creator = m_document->descriptionSyntaxHighlighterCreator();
-    if (creator)
-        m_descriptionWidget->textDocument()->resetSyntaxHighlighter(creator);
-}
-
 void DiffEditor::contextLineCountHasChanged(int lines)
 {
     QTC_ASSERT(!m_document->isContextLineCountForced(), return);
diff --git a/src/plugins/diffeditor/diffeditorcontroller.cpp b/src/plugins/diffeditor/diffeditorcontroller.cpp
index d746e5bcb68..d669b7b1f19 100644
--- a/src/plugins/diffeditor/diffeditorcontroller.cpp
+++ b/src/plugins/diffeditor/diffeditorcontroller.cpp
@@ -93,12 +93,6 @@ void DiffEditorController::setDescription(const QString &description)
     m_document->setDescription(description);
 }
 
-void DiffEditorController::setDescriptionSyntaxHighlighterCreator(
-    const std::function<TextEditor::SyntaxHighlighter *()> &creator)
-{
-    m_document->setDescriptionSyntaxHighlighterCreator(creator);
-}
-
 /**
  * @brief Force the lines of context to the given number.
  *
diff --git a/src/plugins/diffeditor/diffeditorcontroller.h b/src/plugins/diffeditor/diffeditorcontroller.h
index 6ef7b8a7925..a0ede4d0d6d 100644
--- a/src/plugins/diffeditor/diffeditorcontroller.h
+++ b/src/plugins/diffeditor/diffeditorcontroller.h
@@ -16,7 +16,6 @@ class QMenu;
 QT_END_NAMESPACE
 
 namespace Core { class IDocument; }
-namespace TextEditor { class SyntaxHighlighter; }
 namespace Utils { class FilePath; }
 
 namespace DiffEditor {
@@ -65,8 +64,6 @@ protected:
     void setDisplayName(const QString &name) { m_displayName = name; }
     void setAnsiEnabled(bool enabled);
     void setDescription(const QString &description);
-    void setDescriptionSyntaxHighlighterCreator(
-        const std::function<TextEditor::SyntaxHighlighter *()> &creator);
     void setStartupFile(const QString &startupFile);
     void forceContextLineCount(int lines);
 
diff --git a/src/plugins/diffeditor/diffeditordocument.cpp b/src/plugins/diffeditor/diffeditordocument.cpp
index d5b010c3d8a..9b456a152df 100644
--- a/src/plugins/diffeditor/diffeditordocument.cpp
+++ b/src/plugins/diffeditor/diffeditordocument.cpp
@@ -179,13 +179,6 @@ void DiffEditorDocument::setDescription(const QString &description)
     emit descriptionChanged();
 }
 
-void DiffEditorDocument::setDescriptionSyntaxHighlighterCreator(
-    const std::function<TextEditor::SyntaxHighlighter *()> &creator)
-{
-    m_descriptionHighlighter = creator;
-    emit descriptionHighlighterChanged();
-}
-
 QString DiffEditorDocument::description() const
 {
     return m_description;
diff --git a/src/plugins/diffeditor/diffeditordocument.h b/src/plugins/diffeditor/diffeditordocument.h
index dcace5932fa..9dcf017dccd 100644
--- a/src/plugins/diffeditor/diffeditordocument.h
+++ b/src/plugins/diffeditor/diffeditordocument.h
@@ -8,8 +8,6 @@
 #include <coreplugin/patchtool.h>
 #include <coreplugin/textdocument.h>
 
-namespace TextEditor { class SyntaxHighlighter; }
-
 namespace DiffEditor {
 
 class DiffEditorController;
@@ -49,11 +47,6 @@ public:
     QString description() const;
     void setDescriptionAnsiEnabled(bool enabled) { m_descriptionAnsiEnabled = enabled; }
     bool isDescriptionAnsiEnabled() const { return m_descriptionAnsiEnabled; }
-    void setDescriptionSyntaxHighlighterCreator(
-        const std::function<TextEditor::SyntaxHighlighter *()> &creator);
-    std::function<TextEditor::SyntaxHighlighter *()> descriptionSyntaxHighlighterCreator() const {
-        return m_descriptionHighlighter;
-    }
 
     void setContextLineCount(int lines);
     int contextLineCount() const;
@@ -80,7 +73,6 @@ signals:
     void temporaryStateChanged();
     void documentChanged();
     void descriptionChanged();
-    void descriptionHighlighterChanged();
 
 protected:
     bool saveImpl(QString *errorString, const Utils::FilePath &filePath, bool autoSave) override;
@@ -95,7 +87,6 @@ private:
     Utils::FilePath m_workingDirectory;
     QString m_startupFile;
     QString m_description;
-    std::function<TextEditor::SyntaxHighlighter *()> m_descriptionHighlighter = {};
     int m_contextLineCount = 3;
     bool m_isContextLineCountForced = false;
     bool m_ignoreWhitespace = false;