diff --git a/xwl/drag_x.cpp b/xwl/drag_x.cpp
--- a/xwl/drag_x.cpp
+++ b/xwl/drag_x.cpp
@@ -69,13 +69,12 @@
         // we use this mechanism, because the finished call is not
         // reliable done by Wayland clients
         auto it = std::find_if(m_dataRequests.begin(), m_dataRequests.end(), [eventTime](const QPair<xcb_timestamp_t, bool> &req) {
-            return req.first == eventTime;
+            return req.first == eventTime && req.second == false;
         });
         if (it == m_dataRequests.end()) {
             // transfer finished for a different drag
             return;
         }
-        Q_ASSERT(!(*it).second);
         (*it).second = true;
         checkForFinished();
     });