diff --git a/os/src/test/signal/main.cc b/os/src/test/signal/main.cc
index c4338e0f4..ba26cfe81 100644
--- a/os/src/test/signal/main.cc
+++ b/os/src/test/signal/main.cc
@@ -51,10 +51,11 @@ class Sender : Thread<4096>
 						printf("submit signal %d\n", _submit_cnt);
 
 					_transmitter.submit();
-				}
 
-				if (_interval_ms)
-					_timer.msleep(_interval_ms);
+					if (_interval_ms)
+						_timer.msleep(_interval_ms);
+				} else
+					_timer.msleep(100);
 			}
 		}