diff --git a/c/cli/mlrcli.c b/c/cli/mlrcli.c
index 6a96939b9..ee912aca4 100644
--- a/c/cli/mlrcli.c
+++ b/c/cli/mlrcli.c
@@ -725,6 +725,7 @@ cli_opts_t* parse_command_line(int argc, char** argv) {
 		} else if (streq(argv[argi], "--prepipe")) {
 			check_arg_count(argv, argi, argc, 2);
 			popts->prepipe = argv[argi+1];
+			popts->use_mmap_for_read = FALSE;
 			argi++;
 
 		} else {
diff --git a/c/todo.txt b/c/todo.txt
index 723ae1820..f85e7e1d8 100644
--- a/c/todo.txt
+++ b/c/todo.txt
@@ -18,6 +18,7 @@ TOP OF LIST
   - doc why not libs
   - consider popen output, but probably just suggest pipe.
   - UT join w/ mixed left/right compressed/not
+  - mlr -h, mld section, etc.
 
 * more perf tuning:
   - strict power-of-two malloc/strdups thruout?!? profile.