diff --git a/share/man/man7/build.7 b/share/man/man7/build.7
--- a/share/man/man7/build.7
+++ b/share/man/man7/build.7
@@ -650,6 +650,20 @@
 the root of the source tree to build as part of the
 .Cm cross-tools
 target.
+.It Va PKG_FORMAT
+Specify a package compression format when building
+.Pa src
+into
+.Cm packages .
+Accepts one of
+.Dv tbz ,
+.Dv tgz ,
+.Dv txz ,
+.Dv tzst ,
+or
+.Dv tar Pq uncompressed .
+Default:
+.Dv tzst .
 .It Va PORTS_MODULES
 A list of ports with kernel modules that should be built and installed
 as part of the