diff --git a/doc/snac.1 b/doc/snac.1
index 2ef1625..855c09f 100644
--- a/doc/snac.1
+++ b/doc/snac.1
@@ -204,6 +204,12 @@ Enqueues a Create + Note message to all followers. If the
 argument is -e,  the external editor defined by the EDITOR
 environment variable will be invoked to prepare a message; if
 it's - (a lonely hyphen), the post content will be read from stdin.
+.It Cm block Ar basedir Ar instance_url
+Blocks a full instance, given its URL or domain name. All subsequent
+incoming activities with identifiers from that instance will be immediately
+blocked without further inspection.
+.It Cm unblock Ar basedir Ar instance_url
+Unblocks a previously blocked instance.
 .El
 .Ss Migrating an account from Mastodon
 See 
diff --git a/doc/snac.8 b/doc/snac.8
index 65167b7..fb170e0 100644
--- a/doc/snac.8
+++ b/doc/snac.8
@@ -281,6 +281,10 @@ format) from the Mastodon web interface and execute this:
 awk -F, 'NR > 1 { print $1 }' /path/to/following_accounts.csv | \\
 xargs -n 1 snac follow $SNAC_BASEDIR $SNAC_USER
 .Ed
+.Ss Instance blocking
+Full instances can be blocked. This operation must be done from
+the command-line tool. See
+.Xr snac 1 .
 .Ss Other Considerations
 .Nm
 stores all the messages it receives as JSON files, which are usually