diff --git a/share/man/man5/fstab.5 b/share/man/man5/fstab.5
index df19b9be8af..1c6f17e40c5 100644
--- a/share/man/man5/fstab.5
+++ b/share/man/man5/fstab.5
@@ -198,6 +198,8 @@ command to determine which file systems need to be dumped.
 If the fifth field is not present, a value of zero is returned and
 .Nm dump
 will assume that the file system does not need to be dumped.
+If the fifth field is greater than 0, then it specifies the number of days
+between dumps for this file system.
 .Pp
 The sixth field,
 .Pq Fa fs_passno ,