diff --git a/sdk_container/src/third_party/portage-stable/eclass/prefix.eclass b/sdk_container/src/third_party/portage-stable/eclass/prefix.eclass
index 8ae3e3a531..0571dd1fb2 100644
--- a/sdk_container/src/third_party/portage-stable/eclass/prefix.eclass
+++ b/sdk_container/src/third_party/portage-stable/eclass/prefix.eclass
@@ -1,16 +1,25 @@
-# Copyright 1999-2017 Gentoo Foundation
+# Copyright 1999-2021 Gentoo Authors
 # Distributed under the terms of the GNU General Public License v2
 
 # @ECLASS: prefix.eclass
 # @MAINTAINER:
 # Feel free to contact the Prefix team through <prefix@gentoo.org> if
 # you have problems, suggestions or questions.
+# @SUPPORTED_EAPIS: 5 6 7 8
 # @BLURB: Eclass to provide Prefix functionality
 # @DESCRIPTION:
 # Gentoo Prefix allows users to install into a self defined offset
 # located somewhere in the filesystem.  Prefix ebuilds require
 # additional functions and variables which are defined by this eclass.
 
+case ${EAPI:-0} in
+	[5678]) ;;
+	*) die "${ECLASS}: EAPI ${EAPI:-0} not supported" ;;
+esac
+
+if [[ -z ${_PREFIX_ECLASS} ]]; then
+_PREFIX_ECLASS=1
+
 # @ECLASS-VARIABLE: EPREFIX
 # @DESCRIPTION:
 # The offset prefix of a Gentoo Prefix installation.  When Gentoo Prefix
@@ -111,7 +120,7 @@ hprefixify() {
 }
 
 # @FUNCTION: prefixify_ro
-# @USAGE: prefixify_ro <file>.
+# @USAGE: <file>
 # @DESCRIPTION:
 # prefixify a read-only file.
 # copies the files to ${T}, prefixies it, echos the new file.
@@ -136,3 +145,5 @@ prefixify_ro() {
 	fi
 }
 # vim: tw=72:
+
+fi