diff --git a/yue.py b/yue.py
index 1cb3885..5ded276 100644
--- a/yue.py
+++ b/yue.py
@@ -55,7 +55,7 @@ def at(t):
     ret = 0
     for j in range(max(i - 32, 0), i):
         m = music[j]
-        if m[1] > t:
+        if m[1] > t and m[2] > 0:
             ret += m[4] * m[5](freq(m[2], m[3]), t - m[0])
     return int(2**28 * ret)