diff --git a/xpra/x11/x11_server_core.py b/xpra/x11/x11_server_core.py
index 35f41d6a75..e42ae189fb 100644
--- a/xpra/x11/x11_server_core.py
+++ b/xpra/x11/x11_server_core.py
@@ -776,7 +776,7 @@ def set_screen_size(self, desired_w:int, desired_h:int, bigger:bool=True):
             screenlog("using XRRSetScreenConfigAndRate with %ix%i", w, h)
             with xsync:
                 RandR.set_screen_size(w, h)
-            if RandR.check_randr():
+            if RandR.check_randr_sizes():
                 #Xvfb with randr > 1.2
                 #we can use XRRSetScreenSize:
                 try: