diff --git a/c/cli/mlrcli.c b/c/cli/mlrcli.c
index f70d1390a..7dc38dfcf 100644
--- a/c/cli/mlrcli.c
+++ b/c/cli/mlrcli.c
@@ -261,7 +261,7 @@ cli_opts_t* parse_command_line(int argc, char** argv, sllv_t** ppmapper_list) {
 		slls_append(popts->filenames, argv[argi], NO_FREE);
 	}
 
-	// Check for use of mmap. It's fractionally faster than stdio (due to fewer data copies
+	// Check for use of mmap. It's about 20% faster than stdio (due to fewer data copies
 	// -- lrecs can be pointer-backed by mmap memory) but we can't use it in all situations.
 	if (no_input) {
 		slls_free(popts->filenames);
@@ -269,6 +269,10 @@ cli_opts_t* parse_command_line(int argc, char** argv, sllv_t** ppmapper_list) {
 	} else if (popts->filenames->length == 0) {
 		// No filenames means read from standard input, and standard input cannot be mmapped.
 		popts->reader_opts.use_mmap_for_read = FALSE;
+	} else if (popts->filenames->length > 10) {
+		// https://github.com/johnkerl/miller/issues/256: too many small files is as bad as one big one
+		// (for which see immediately below).
+		popts->reader_opts.use_mmap_for_read = FALSE;
 	} else if (popts->reader_opts.use_mmap_for_read == TRUE) {
 		// https://github.com/johnkerl/miller/issues/160: don't use mmap for large files.
 		//
diff --git a/doc/manpage.html b/doc/manpage.html
index f5cbaca55..176daed80 100644
--- a/doc/manpage.html
+++ b/doc/manpage.html
@@ -2464,7 +2464,7 @@ SEE ALSO
 
 
 
-				  2019-06-04			     MILLER(1)
+				  2019-08-24			     MILLER(1)
 </pre>
 </div>
 <p/>
diff --git a/doc/manpage.txt b/doc/manpage.txt
index d0b0065bd..498006063 100644
--- a/doc/manpage.txt
+++ b/doc/manpage.txt
@@ -2270,4 +2270,4 @@ SEE ALSO
 
 
 
-				  2019-06-04			     MILLER(1)
+				  2019-08-24			     MILLER(1)
diff --git a/doc/mlr.1 b/doc/mlr.1
index 2fd8f6b4b..0dc55659c 100644
--- a/doc/mlr.1
+++ b/doc/mlr.1
@@ -2,12 +2,12 @@
 .\"     Title: mlr
 .\"    Author: [see the "AUTHOR" section]
 .\" Generator: ./mkman.rb
-.\"      Date: 2019-06-04
+.\"      Date: 2019-08-24
 .\"    Manual: \ \&
 .\"    Source: \ \&
 .\"  Language: English
 .\"
-.TH "MILLER" "1" "2019-06-04" "\ \&" "\ \&"
+.TH "MILLER" "1" "2019-08-24" "\ \&" "\ \&"
 .\" -----------------------------------------------------------------
 .\" * Portability definitions
 .\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~