diff --git a/feh.1 b/feh.1
index 22850ed18ff94de809de8fab4b989813577555b0..094d66fc17cd6c1446b1b37a2179c7234ab8d9fc 100644
--- a/feh.1
+++ b/feh.1
@@ -426,10 +426,10 @@ made transparent.
 When drawing thumbnails onto the background, apply them with a transparency
 level of NUM (0-255).
 .TP 5
-.B -o FILE
+.B -o, --output FILE
 Save the created montage to FILE
 .TP 5
-.B -O FILE
+.B -O, --output-only FILE
 Just save the created montage to FILE without displaying it (use in scripts)
 .SH INDEX MODE OPTIONS
 .TP 5
diff --git a/src/options.c b/src/options.c
index 06efb85cf3496e458063df2b1f55cbff3eddea8c..14d52b797304b5b36dd5cfd184e13feb677fb8de 100644
--- a/src/options.c
+++ b/src/options.c
@@ -1082,8 +1082,8 @@ show_usage(void)
 "                           make the background transparent.\n"
 " -a, --alpha NUM           When drawing thumbnails onto the background, apply\n"
 "                           them with a transparency level of NUM (0-255).\n"
-" -o FILE                   Save the created montage to FILE\n"
-" -O FILE                   Just save the created montage to FILE\n"
+" -o, --output FILE         Save the created montage to FILE\n"
+" -O, --output-only  FILE   Just save the created montage to FILE\n"
 "                           WITHOUT displaying it (use in scripts)\n"
 " INDEX MODE OPTIONS\n"
 " -e FONT                   Use FONT to print the information under each\n"