diff --git a/src/plugins/diffeditor/diffeditor.h b/src/plugins/diffeditor/diffeditor.h
index 0777aed00e5..6da073439da 100644
--- a/src/plugins/diffeditor/diffeditor.h
+++ b/src/plugins/diffeditor/diffeditor.h
@@ -35,7 +35,6 @@ QT_BEGIN_NAMESPACE
 class QComboBox;
 class QSpinBox;
 class QToolBar;
-class QToolButton;
 class QStackedWidget;
 QT_END_NAMESPACE
 
diff --git a/src/plugins/diffeditor/diffview.h b/src/plugins/diffeditor/diffview.h
index 34c473d00c4..cbdc2cbdfde 100644
--- a/src/plugins/diffeditor/diffview.h
+++ b/src/plugins/diffeditor/diffview.h
@@ -37,7 +37,6 @@ namespace TextEditor { class TextEditorWidget; }
 
 namespace DiffEditor {
 
-class DiffEditorController;
 class FileData;
 
 namespace Internal {
diff --git a/src/plugins/diffeditor/sidebysidediffeditorwidget.h b/src/plugins/diffeditor/sidebysidediffeditorwidget.h
index 2b03308c9eb..4f97494b804 100644
--- a/src/plugins/diffeditor/sidebysidediffeditorwidget.h
+++ b/src/plugins/diffeditor/sidebysidediffeditorwidget.h
@@ -44,7 +44,6 @@ QT_END_NAMESPACE
 
 namespace DiffEditor {
 
-class DiffEditorController;
 class FileData;
 
 namespace Internal {
diff --git a/src/plugins/diffeditor/unifieddiffeditorwidget.h b/src/plugins/diffeditor/unifieddiffeditorwidget.h
index c05d05e9af1..3e697f7b439 100644
--- a/src/plugins/diffeditor/unifieddiffeditorwidget.h
+++ b/src/plugins/diffeditor/unifieddiffeditorwidget.h
@@ -35,11 +35,6 @@ class DisplaySettings;
 class FontSettings;
 }
 
-QT_BEGIN_NAMESPACE
-class QSplitter;
-class QTextCharFormat;
-QT_END_NAMESPACE
-
 namespace DiffEditor {
 
 class ChunkData;