diff --git a/src/plugins/projectexplorer/projectexplorer.cpp b/src/plugins/projectexplorer/projectexplorer.cpp
index a1557ef272d..b15cad5cb83 100644
--- a/src/plugins/projectexplorer/projectexplorer.cpp
+++ b/src/plugins/projectexplorer/projectexplorer.cpp
@@ -315,7 +315,6 @@ public:
     void duplicateFile();
     void deleteFile();
     void handleRenameFile();
-    void handleDiffFile();
     void handleSetStartupProject();
     void setStartupProject(ProjectExplorer::Project *project);
 
@@ -1118,7 +1117,8 @@ bool ProjectExplorerPlugin::initialize(const QStringList &arguments, QString *er
     mfileContextMenu->addAction(cmd, Constants::G_FILE_OTHER);
 
     // diff file action
-    dd->m_diffFileAction = new QAction(tr("Diff Against Current File"), this);
+    dd->m_diffFileAction = TextEditor::TextDocument::createDiffAgainstCurrentFileAction(
+        this, &ProjectTree::currentFilePath);
     cmd = ActionManager::registerAction(dd->m_diffFileAction, Constants::DIFFFILE, projecTreeContext);
     mfileContextMenu->addAction(cmd, Constants::G_FILE_OTHER);
 
@@ -1362,8 +1362,6 @@ bool ProjectExplorerPlugin::initialize(const QStringList &arguments, QString *er
             dd, &ProjectExplorerPluginPrivate::deleteFile);
     connect(dd->m_renameFileAction, &QAction::triggered,
             dd, &ProjectExplorerPluginPrivate::handleRenameFile);
-    connect(dd->m_diffFileAction, &QAction::triggered,
-            dd, &ProjectExplorerPluginPrivate::handleDiffFile);
     connect(dd->m_setStartupProjectAction, &QAction::triggered,
             dd, &ProjectExplorerPluginPrivate::handleSetStartupProject);
     connect(dd->m_projectTreeCollapseAllAction, &QAction::triggered,
@@ -3379,39 +3377,6 @@ void ProjectExplorerPluginPrivate::handleRenameFile()
     }
 }
 
-void ProjectExplorerPluginPrivate::handleDiffFile()
-{
-    // current editor's file
-    auto textDocument = TextEditor::TextDocument::currentTextDocument();
-
-    if (!textDocument)
-        return;
-
-    const QString leftFileName = textDocument->filePath().toString();
-
-    if (leftFileName.isEmpty())
-        return;
-
-    // current item's file
-    Node *currentNode = ProjectTree::findCurrentNode();
-    QTC_ASSERT(currentNode && currentNode->nodeType() == NodeType::File, return);
-
-    FileNode *fileNode = currentNode->asFileNode();
-
-    if (!fileNode)
-        return;
-
-    const QString rightFileName = currentNode->filePath().toString();
-    if (rightFileName.isEmpty())
-        return;
-
-    if (!isTextFile(rightFileName))
-        return;
-
-    if (auto diffService = ExtensionSystem::PluginManager::getObject<DiffService>())
-        diffService->diffFiles(leftFileName, rightFileName);
-}
-
 void ProjectExplorerPlugin::renameFile(Node *node, const QString &newFilePath)
 {
     const QString oldFilePath = node->filePath().toFileInfo().absoluteFilePath();
diff --git a/src/plugins/projectexplorer/projecttree.cpp b/src/plugins/projectexplorer/projecttree.cpp
index 69bbeb8a075..b8db32c3974 100644
--- a/src/plugins/projectexplorer/projecttree.cpp
+++ b/src/plugins/projectexplorer/projecttree.cpp
@@ -110,6 +110,12 @@ Node *ProjectTree::findCurrentNode()
     return s_instance->m_currentNode;
 }
 
+FileName ProjectTree::currentFilePath()
+{
+    Node *currentNode = findCurrentNode();
+    return currentNode ? currentNode->filePath() : FileName();
+}
+
 void ProjectTree::registerWidget(ProjectTreeWidget *widget)
 {
     s_instance->m_projectTreeWidgets.append(widget);
diff --git a/src/plugins/projectexplorer/projecttree.h b/src/plugins/projectexplorer/projecttree.h
index 684d4b731a8..f127b155f74 100644
--- a/src/plugins/projectexplorer/projecttree.h
+++ b/src/plugins/projectexplorer/projecttree.h
@@ -31,6 +31,8 @@
 
 #include <functional>
 
+namespace Utils { class FileName; }
+
 namespace ProjectExplorer {
 class FileNode;
 class FolderNode;
@@ -52,6 +54,7 @@ public:
 
     static Project *currentProject();
     static Node *findCurrentNode();
+    static Utils::FileName currentFilePath();
 
     // Integration with ProjectTreeWidget
     static void registerWidget(Internal::ProjectTreeWidget *widget);
diff --git a/src/plugins/texteditor/textdocument.cpp b/src/plugins/texteditor/textdocument.cpp
index 9e8befb9391..404007382b4 100644
--- a/src/plugins/texteditor/textdocument.cpp
+++ b/src/plugins/texteditor/textdocument.cpp
@@ -36,12 +36,15 @@
 #include "texteditorconstants.h"
 #include "typingsettings.h"
 #include <texteditor/generichighlighter/highlighter.h>
+#include <coreplugin/diffservice.h>
 #include <coreplugin/editormanager/editormanager.h>
 #include <coreplugin/editormanager/documentmodel.h>
+#include <extensionsystem/pluginmanager.h>
 #include <utils/textutils.h>
 #include <utils/guard.h>
 #include <utils/mimetypes/mimedatabase.h>
 
+#include <QAction>
 #include <QApplication>
 #include <QDir>
 #include <QFileInfo>
@@ -357,6 +360,22 @@ void TextDocument::setFontSettings(const FontSettings &fontSettings)
     emit fontSettingsChanged();
 }
 
+QAction *TextDocument::createDiffAgainstCurrentFileAction(
+    QObject *parent, const std::function<Utils::FileName()> &filePath)
+{
+    const auto diffAgainstCurrentFile = [filePath]() {
+        auto diffService = ExtensionSystem::PluginManager::getObject<DiffService>();
+        auto textDocument = TextEditor::TextDocument::currentTextDocument();
+        const QString leftFilePath = textDocument ? textDocument->filePath().toString() : QString();
+        const QString rightFilePath = filePath().toString();
+        if (diffService && !leftFilePath.isEmpty() && !rightFilePath.isEmpty())
+            diffService->diffFiles(leftFilePath, rightFilePath);
+    };
+    auto diffAction = new QAction(tr("Diff Against Current File"), parent);
+    QObject::connect(diffAction, &QAction::triggered, parent, diffAgainstCurrentFile);
+    return diffAction;
+}
+
 void TextDocument::triggerPendingUpdates()
 {
     if (d->m_fontSettingsNeedsApply)
diff --git a/src/plugins/texteditor/textdocument.h b/src/plugins/texteditor/textdocument.h
index eecaa838233..65caa2b2e6f 100644
--- a/src/plugins/texteditor/textdocument.h
+++ b/src/plugins/texteditor/textdocument.h
@@ -35,6 +35,7 @@
 #include <QSharedPointer>
 
 QT_BEGIN_NAMESPACE
+class QAction;
 class QTextCursor;
 class QTextDocument;
 QT_END_NAMESPACE
@@ -138,6 +139,9 @@ public:
     void setTabSettings(const TextEditor::TabSettings &tabSettings);
     void setFontSettings(const TextEditor::FontSettings &fontSettings);
 
+    static QAction *createDiffAgainstCurrentFileAction(QObject *parent,
+        const std::function<Utils::FileName()> &filePath);
+
 signals:
     void aboutToOpen(const QString &fileName, const QString &realFileName);
     void openFinishedSuccessfully();