diff --git a/src/nvim/testdir/shared.vim b/src/nvim/testdir/shared.vim
index 29af05fe3f..5dea33e2ac 100644
--- a/src/nvim/testdir/shared.vim
+++ b/src/nvim/testdir/shared.vim
@@ -156,7 +156,7 @@ func WaitFor(expr, ...)
     endif
     sleep 10m
   endfor
-  return timeout
+  throw 'WaitFor() timed out after ' . timeout . ' msec'
 endfunc
 
 " Wait for up to a given milliseconds.