diff --git a/runtime/indent/testdir/runtest.vim b/runtime/indent/testdir/runtest.vim
index 5d36512..1cc0d3f 100644
--- a/runtime/indent/testdir/runtest.vim
+++ b/runtime/indent/testdir/runtest.vim
@@ -1,4 +1,6 @@
-" Runs all the indent tests for which there is no .out file
+" Runs all the indent tests for which there is no .out file.
+"
+" Current directory must be runtime/indent.
 
 set nocp
 filetype indent on