diff --git a/aquaPi/machineroom/out_nodes.py b/aquaPi/machineroom/out_nodes.py
index bbf9139..4bc1157 100644
--- a/aquaPi/machineroom/out_nodes.py
+++ b/aquaPi/machineroom/out_nodes.py
@@ -190,7 +190,7 @@ def toggle_and_wait(state: bool, end: float) -> bool:
                     self._thread_stop = False
                     return False
                 time.sleep(.1)
-            time.sleep(end - time.time())
+            time.sleep(max(0, end - time.time()))
             log.debug('  _pulse needed %f instead of %f',
                       time.time() - start, end - start)
             return True