diff --git a/qt-ui/simplewidgets.cpp b/qt-ui/simplewidgets.cpp
index 430609c7b..d060e3892 100644
--- a/qt-ui/simplewidgets.cpp
+++ b/qt-ui/simplewidgets.cpp
@@ -143,14 +143,16 @@ void RenumberDialog::renumberOnlySelected(bool selected)
 void RenumberDialog::buttonClicked(QAbstractButton *button)
 {
 	if (ui.buttonBox->buttonRole(button) == QDialogButtonBox::AcceptRole) {
-		QMap<int,int> renumberedDives;
+		// we remember a map from dive uuid to a pair of old number / new number
+		QMap<int,QPair<int, int> > renumberedDives;
 		int i;
+		int newNr = ui.spinBox->value();
 		struct dive *dive = NULL;
 		for_each_dive (i, dive) {
 			if (!selectedOnly || dive->selected)
-				renumberedDives.insert(dive->id, dive->number);
+				renumberedDives.insert(dive->id, QPair<int,int>(dive->number, newNr++));
 		}
-		UndoRenumberDives *undoCommand = new UndoRenumberDives(renumberedDives, ui.spinBox->value());
+		UndoRenumberDives *undoCommand = new UndoRenumberDives(renumberedDives);
 		MainWindow::instance()->undoStack->push(undoCommand);
 	}
 }
diff --git a/qt-ui/undocommands.cpp b/qt-ui/undocommands.cpp
index aad264e24..d7bae75a9 100644
--- a/qt-ui/undocommands.cpp
+++ b/qt-ui/undocommands.cpp
@@ -63,20 +63,20 @@ void UndoShiftTime::redo()
 }
 
 
-UndoRenumberDives::UndoRenumberDives(QMap<int, int> originalNumbers, int startNumber)
+UndoRenumberDives::UndoRenumberDives(QMap<int, QPair<int, int> > originalNumbers)
 {
 	oldNumbers = originalNumbers;
-	start = startNumber;
-	setText("renumber dive");
 	if (oldNumbers.count() > 1)
 		setText(QString("renumber %1 dives").arg(QString::number(oldNumbers.count())));
+	else
+		setText("renumber dive");
 }
 
 void UndoRenumberDives::undo()
 {
 	foreach (int key, oldNumbers.keys()) {
 		struct dive* d = get_dive_by_uniq_id(key);
-		d->number = oldNumbers.value(key);
+		d->number = oldNumbers.value(key).first;
 	}
 	mark_divelist_changed(true);
 	MainWindow::instance()->refreshDisplay();
@@ -84,10 +84,9 @@ void UndoRenumberDives::undo()
 
 void UndoRenumberDives::redo()
 {
-	int i = start;
 	foreach (int key, oldNumbers.keys()) {
 		struct dive* d = get_dive_by_uniq_id(key);
-		d->number = i++;
+		d->number = oldNumbers.value(key).second;
 	}
 	mark_divelist_changed(true);
 	MainWindow::instance()->refreshDisplay();
diff --git a/qt-ui/undocommands.h b/qt-ui/undocommands.h
index bd8530d77..62fb2d22b 100644
--- a/qt-ui/undocommands.h
+++ b/qt-ui/undocommands.h
@@ -28,13 +28,12 @@ private:
 
 class UndoRenumberDives : public QUndoCommand {
 public:
-	UndoRenumberDives(QMap<int,int> originalNumbers, int startNumber);
+	UndoRenumberDives(QMap<int, QPair<int, int> > originalNumbers);
 	virtual void undo();
 	virtual void redo();
 
 private:
-	QMap<int,int> oldNumbers;
-	int start;
+	QMap<int,QPair<int, int> > oldNumbers;
 };
 
 class UndoRemoveDivesFromTrip : public QUndoCommand {