diff --git a/src/testdir/test_timers.vim b/src/testdir/test_timers.vim
index e0d024b..383aff5 100644
--- a/src/testdir/test_timers.vim
+++ b/src/testdir/test_timers.vim
@@ -290,6 +290,7 @@
   if has('win32') && !has('gui_running')
     throw 'Skipped: cannot get low-level input'
   endif
+  CheckFunction reltimefloat
 
   " Measure the elapsed time to avoid a hang when it fails.
   let start = reltime()