diff --git a/lib/abstractimageoperation.h b/lib/abstractimageoperation.h
--- a/lib/abstractimageoperation.h
+++ b/lib/abstractimageoperation.h
@@ -58,6 +58,8 @@
     void applyToDocument(Document::Ptr);
     Document::Ptr document() const;
 
+    void finishUndoJob();
+
 protected:
     virtual void redo() = 0;
     virtual void undo()
diff --git a/lib/abstractimageoperation.cpp b/lib/abstractimageoperation.cpp
--- a/lib/abstractimageoperation.cpp
+++ b/lib/abstractimageoperation.cpp
@@ -23,6 +23,7 @@
 
 // Qt
 #include <QUrl>
+#include <QTimer>
 
 // KDE
 #include <KJob>
@@ -90,6 +91,7 @@
         ImageOperationCommand* command = new ImageOperationCommand(this);
         command->setText(d->mText);
         document()->undoStack()->push(command);
+        document()->imageOperationCompleted();
     } else {
         deleteLater();
     }
@@ -100,6 +102,13 @@
     finish(job->error() == KJob::NoError);
 }
 
+void AbstractImageOperation::finishUndoJob()
+{
+    // Give QUndoStack time to update in case the undo is executed immediately
+    // (e.g. undo crop just sets the previous image)
+    QTimer::singleShot(0, document().data(), &Document::imageOperationCompleted);
+}
+
 void AbstractImageOperation::setText(const QString& text)
 {
     d->mText = text;
diff --git a/lib/crop/cropimageoperation.cpp b/lib/crop/cropimageoperation.cpp
--- a/lib/crop/cropimageoperation.cpp
+++ b/lib/crop/cropimageoperation.cpp
@@ -89,6 +89,7 @@
         return;
     }
     document()->editor()->setImage(d->mOriginalImage);
+    finishUndoJob();
 }
 
 } // namespace
diff --git a/lib/document/document.h b/lib/document/document.h
--- a/lib/document/document.h
+++ b/lib/document/document.h
@@ -197,6 +197,8 @@
 
     void enqueueJob(DocumentJob*);
 
+    void imageOperationCompleted();
+
     /**
      * Returns true if there are queued tasks for this document.
      */
@@ -220,7 +222,6 @@
     void emitMetaInfoLoaded();
     void emitLoaded();
     void emitLoadingFailed();
-    void slotUndoIndexChanged();
     void slotSaveResult(KJob*);
     void slotJobFinished(KJob*);
 
diff --git a/lib/document/document.cpp b/lib/document/document.cpp
--- a/lib/document/document.cpp
+++ b/lib/document/document.cpp
@@ -154,7 +154,6 @@
     d->mImpl = 0;
     d->mUrl = url;
     d->mKeepRawData = false;
-    connect(&d->mUndoStack, SIGNAL(indexChanged(int)), SLOT(slotUndoIndexChanged()));
 
     reload();
 }
@@ -483,7 +482,7 @@
     return &d->mUndoStack;
 }
 
-void Document::slotUndoIndexChanged()
+void Document::imageOperationCompleted()
 {
     if (d->mUndoStack.isClean()) {
         // If user just undid all his changes this does not really correspond
diff --git a/lib/redeyereduction/redeyereductionimageoperation.cpp b/lib/redeyereduction/redeyereductionimageoperation.cpp
--- a/lib/redeyereduction/redeyereductionimageoperation.cpp
+++ b/lib/redeyereduction/redeyereductionimageoperation.cpp
@@ -104,6 +104,7 @@
         painter.drawImage(rect.topLeft(), d->mOriginalImage);
     }
     document()->editor()->setImage(img);
+    finishUndoJob();
 }
 
 /**
diff --git a/lib/resize/resizeimageoperation.cpp b/lib/resize/resizeimageoperation.cpp
--- a/lib/resize/resizeimageoperation.cpp
+++ b/lib/resize/resizeimageoperation.cpp
@@ -89,6 +89,7 @@
         return;
     }
     document()->editor()->setImage(d->mOriginalImage);
+    finishUndoJob();
 }
 
 } // namespace
diff --git a/lib/thumbnailview/thumbnailview.cpp b/lib/thumbnailview/thumbnailview.cpp
--- a/lib/thumbnailview/thumbnailview.cpp
+++ b/lib/thumbnailview/thumbnailview.cpp
@@ -876,7 +876,7 @@
         return;
     }
 
-    if (d->mDocumentInfoProvider && d->mDocumentInfoProvider->isModified(url)) {
+    if (d->mDocumentInfoProvider) {
         d->updateThumbnailForModifiedDocument(it->mIndex);
     } else {
         const KFileItem item = fileItemForIndex(it->mIndex);
diff --git a/lib/transformimageoperation.cpp b/lib/transformimageoperation.cpp
--- a/lib/transformimageoperation.cpp
+++ b/lib/transformimageoperation.cpp
@@ -101,7 +101,10 @@
         orientation = d->mOrientation;
         break;
     }
-    document()->enqueueJob(new TransformJob(orientation));
+
+    TransformJob* job = new TransformJob(orientation);
+    connect(job, &TransformJob::result, this, &AbstractImageOperation::finishUndoJob);
+    document()->enqueueJob(job);
 }
 
 } // namespace
diff --git a/tests/auto/documenttest.cpp b/tests/auto/documenttest.cpp
--- a/tests/auto/documenttest.cpp
+++ b/tests/auto/documenttest.cpp
@@ -671,9 +671,11 @@
     QCOMPARE(modifiedSpy.count(), 2);
 
     doc->undoStack()->undo();
+    QTest::qWait(100);
     QCOMPARE(modifiedSpy.count(), 3);
 
     doc->undoStack()->undo();
+    QTest::qWait(100);
     QCOMPARE(savedSpy.count(), 1);
 }