diff --git a/docs/mm.1 b/docs/mm.1
index 01790fd..6a1f664 100644
--- a/docs/mm.1
+++ b/docs/mm.1
@@ -37,13 +37,16 @@ Use the standard error as an output.
 .B -i
 .RS
 Opens a path as an input. Without any inputs specified mm will use the
-standard input.
+standard input. The standard input shall be used as an input if one or more of
+the input files is “-”.
 .RE
 
 .B -o
 .RS
 Opens a path as an output. Without any outputs specified mm will use the
-standard output.
+standard output. The standard output shall be used as an output if one or more
+of the output files is “-”.
+
 .RE
 
 .B -u
@@ -56,11 +59,6 @@ Ensures neither input or output will be buffered.
 Causes SIGINT signals to be ignored.
 .RE
 
-.SH STANDARD INPUT
-
-The standard input shall be used as an input if one or more of the input files
-is “-”.
-
 .SH DIAGNOSTICS
 
 If an output can no longer be written mm prints a diagnostic message, ceases