diff --git a/man/vgdisplay.8_pregen b/man/vgdisplay.8_pregen
index e83e8fbea..878762c39 100644
--- a/man/vgdisplay.8_pregen
+++ b/man/vgdisplay.8_pregen
@@ -279,6 +279,7 @@ Use with --separator to align the output columns
 .HP
 \fB-a\fP|\fB--all\fP
 .br
+List all VGs. Equivalent to not specifying any VGs.
 .
 .HP
 \fB--binary\fP