diff --git a/docs/errata.md b/docs/errata.md
index d8066a7..ebbe25c 100644
--- a/docs/errata.md
+++ b/docs/errata.md
@@ -32,3 +32,5 @@ V^{\pi}(s) &\le Q^{\pi}(s,\pi'(s)) \\
 & = V^{\pi'}(s)
 \end{aligned}
 $$
+
+* 229页，第2行：很强的序列 → 很长的序列
\ No newline at end of file