diff --git a/shell_client.h b/shell_client.h
--- a/shell_client.h
+++ b/shell_client.h
@@ -215,7 +215,12 @@
     KWayland::Server::ShellSurfaceInterface *m_shellSurface;
     KWayland::Server::XdgShellSurfaceInterface *m_xdgShellSurface;
     KWayland::Server::XdgShellPopupInterface *m_xdgShellPopup;
+
+    // size of the last buffer
     QSize m_clientSize;
+    // last size we requested or empty if we haven't sent an explicit request to the client
+    // if empty the client should choose their own default size
+    QSize m_requestedClientSize;
 
     struct PendingConfigureRequest {
         //note for wl_shell we have no serial, so serialId and m_lastAckedConfigureRequest will always be 0
diff --git a/shell_client.cpp b/shell_client.cpp
--- a/shell_client.cpp
+++ b/shell_client.cpp
@@ -313,7 +313,7 @@
             if (m_requestGeometryBlockCounter != 0 || areGeometryUpdatesBlocked()) {
                 return;
             }
-            m_xdgShellSurface->configure(xdgSurfaceStates());
+            m_xdgShellSurface->configure(xdgSurfaceStates(), m_requestedClientSize);
         };
         configure();
         connect(this, &AbstractClient::activeChanged, this, configure);
@@ -1184,6 +1184,8 @@
     configureRequest.maximizeMode = m_requestedMaximizeMode;
 
     const QSize size = rect.size() - QSize(borderLeft() + borderRight(), borderTop() + borderBottom());
+    m_requestedClientSize = size;
+
     if (m_shellSurface) {
         m_shellSurface->requestSize(size);
     }
@@ -1262,6 +1264,7 @@
 void ShellClient::unmap()
 {
     m_unmapped = true;
+    m_requestedClientSize = QSize();
     destroyWindowManagementInterface();
     if (Workspace::self()) {
         addWorkspaceRepaint(visibleRect());