diff --git a/error-codes.md b/error-codes.md
index 11e77b1f41931..ba45e329ee2a1 100644
--- a/error-codes.md
+++ b/error-codes.md
@@ -475,7 +475,7 @@ TiDB is compatible with the error codes in MySQL, and in most cases returns the
 
 * Error Number: 9001
 
-    The complete error message: `ERROR 9001 (HY000): PD Server Timeout`
+    The complete error message: `ERROR 9001 (HY000): PD server timeout`
 
     The PD request timed out.
 
@@ -483,7 +483,7 @@ TiDB is compatible with the error codes in MySQL, and in most cases returns the
 
 * Error Number: 9002
 
-    The complete error message: `ERROR 9002 (HY000): TiKV Server Timeout`
+    The complete error message: `ERROR 9002 (HY000): TiKV server timeout`
 
     The TiKV request timed out.