diff --git a/tests/data/test513 b/tests/data/test513
index c30a16d664bd7eaf582ffb9b7e79e8c4eea0bc39..7d8e69b87c99e40ce16faa9d62b190422aeb2884 100644
--- a/tests/data/test513
+++ b/tests/data/test513
@@ -17,7 +17,8 @@ lib513
  <name>
 send HTTP POST using read callback that returns CURL_READFUNC_ABORT
  </name>
- <command>
+# the 1s post-command delay helps to prevent a spurious failure on s390
+ <command delay="1">
 http://%HOSTIP:%HTTPPORT/513
 </command>
 </client>
diff --git a/tests/data/test514 b/tests/data/test514
index bd0bf6bc343a31e292d4caef377b7b2d88c1cf64..bd6da02db189c1c10732164446d2e2d73ca83d49 100644
--- a/tests/data/test514
+++ b/tests/data/test514
@@ -29,7 +29,8 @@ lib514
  <name>
 First set options to POST and then to make HEAD
  </name>
- <command>
+# the 1s post-command delay helps to prevent a spurious failure on s390
+ <command delay="1">
 http://%HOSTIP:%HTTPPORT/514
 </command>
 </client>