diff --git a/src/testdir/test_functions.vim b/src/testdir/test_functions.vim
index 7284787..6c4e813 100644
--- a/src/testdir/test_functions.vim
+++ b/src/testdir/test_functions.vim
@@ -231,7 +231,7 @@
   endif
   let $TZ = 'UTC'
 
-  call assert_equal(1484653763, strptime('%Y-%m-%d %X', '2017-01-17 11:49:23'))
+  call assert_equal(1484653763, strptime('%Y-%m-%d %T', '2017-01-17 11:49:23'))
 
   call assert_fails('call strptime()', 'E119:')
   call assert_fails('call strptime("xxx")', 'E119:')