diff --git a/toonz/sources/toonz/cellselection.cpp b/toonz/sources/toonz/cellselection.cpp
index 0f5c6f1..85d8437 100644
--- a/toonz/sources/toonz/cellselection.cpp
+++ b/toonz/sources/toonz/cellselection.cpp
@@ -2172,6 +2172,8 @@ void TCellSelection::pasteCells() {
             toolHandle->getTool()->onDeactivate();
             toolHandle->getTool()->onActivate();
             rs->pasteSelection();
+            assert(initUndo);
+            TUndoManager::manager()->endBlock();
             return;
           }
         }