diff --git a/debian/changelog b/debian/changelog
index 5713a81..51daae8 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -1,3 +1,15 @@
+base-files (10.3+mendel1) mendel-day; urgency=medium
+
+  * Bump for the Day 4.0 release
+  * Mirror changes to upstream base-files:
+  - Remove VERSION and VERSION_ID from release.
+  - Add CC0-1.0 to common-licenses.
+  - Add Breaks: debian-security-support.
+  - Add VERSION_CODENAME to os-release.
+  - Update Standards-Version to 4.1.3.
+
+ -- Coral <coral-support@google.com>  Tue, 20 Aug 2019 13:40:57 -0700
+
 base-files (9.9+mendel6) mendel-chef; urgency=medium
 
   * Bump for the Chef 3.1 point release
diff --git a/debian/control b/debian/control
index 678aea3..378a335 100644
--- a/debian/control
+++ b/debian/control
@@ -2,7 +2,7 @@
 Section: admin
 Priority: required
 Maintainer: Coral <coral-support@google.com>
-Standards-Version: 3.9.8
+Standards-Version: 4.1.3
 Build-Depends: debhelper (>= 9)
 
 Package: base-files
@@ -13,7 +13,8 @@
 Essential: yes
 Priority: required
 Replaces: base, miscutils, dpkg (<= 1.15.0)
-Breaks: initscripts (<< 2.88dsf-13.3), sendfile (<< 2.1b.20080616-5.2~)
+Breaks: initscripts (<< 2.88dsf-13.3), sendfile (<< 2.1b.20080616-5.2~),
+ debian-security-support (<< 2019.04.25)
 Multi-Arch: foreign
 Description: Mendel base system miscellaneous files
  This package contains the basic filesystem hierarchy of a Mendel system, and
diff --git a/debian/postinst.in b/debian/postinst.in
index 0393a4f..a8c646c 100644
--- a/debian/postinst.in
+++ b/debian/postinst.in
@@ -44,13 +44,13 @@
   fi
 }
 
-if [ -e /etc/dpkg/origins/#VENDORFILE# ]; then
-  ln -sf /etc/dpkg/origins/#VENDORFILE# /etc/dpkg/origins/default
+if [ ! -e /etc/dpkg/origins/default ]; then
+  if [ -e /etc/dpkg/origins/#VENDORFILE# ]; then
+    ln -sf /etc/dpkg/origins/#VENDORFILE# /etc/dpkg/origins/default
+  fi
 fi
 
 if [ "$1" = "configure" ] && [ "$2" = "" ]; then
-  install_from_default staff-group-for-usr-local \
-                                     /etc/staff-group-for-usr-local
   install_from_default dot.profile   /root/.profile
   install_from_default dot.bashrc    /root/.bashrc
   install_from_default profile       /etc/profile
@@ -120,8 +120,3 @@
     install_directory mnt 755 root
   fi
 fi
-
-if dpkg --compare-versions "$2" lt-nl "6.10"; then
-  install_from_default staff-group-for-usr-local \
-    /etc/staff-group-for-usr-local
-fi
diff --git a/debian/rules b/debian/rules
index e0143b0..27740f3 100755
--- a/debian/rules
+++ b/debian/rules
@@ -9,6 +9,7 @@
 endif
 
 VENDORFILE = mendel
+DESTDIR = debian/base-files
 
 %:
 	dh $@
@@ -19,23 +20,6 @@
 	sed -e "s/#VENDORFILE#/$(VENDORFILE)/g" debian/postinst.in > debian/postinst
 
 override_dh_auto_install:
-	debian/rules install DESTDIR=`pwd`/debian/base-files
-
-override_dh_link:
-	dh_link -X os-release
-
-override_dh_compress:
-	dh_compress -X README
-
-override_dh_fixperms:
-	dh_fixperms
-	cd debian/base-files && chown root:staff   var/local
-	cd debian/base-files && chmod 755  `find . -type d`
-	cd debian/base-files && chmod 1777 `cat ../1777-dirs`
-	cd debian/base-files && chmod 2775 `cat ../2775-dirs`
-	cd debian/base-files && chmod 700 root
-
-install:
 	install -p -m 644 etc/*      $(DESTDIR)/etc
 	install -p -m 755 motd/*     $(DESTDIR)/etc/update-motd.d
 	install -p -m 644 licenses/* $(DESTDIR)/usr/share/common-licenses
@@ -51,3 +35,17 @@
 	sed -e "s&#OSNAME#&$(OSNAME)&g" etc/os-release > $(DESTDIR)/etc/os-release
 	mv $(DESTDIR)/etc/os-release $(DESTDIR)/usr/lib/os-release
 	ln -s ../usr/lib/os-release $(DESTDIR)/etc/os-release
+
+override_dh_link:
+	dh_link -X os-release
+
+override_dh_compress:
+	dh_compress -X README
+
+override_dh_fixperms:
+	dh_fixperms
+	cd debian/base-files && chown root:staff   var/local
+	cd debian/base-files && chmod 755  `find . -type d`
+	cd debian/base-files && chmod 1777 `cat ../1777-dirs`
+	cd debian/base-files && chmod 2775 `cat ../2775-dirs`
+	cd debian/base-files && chmod 700 root
diff --git a/etc/debian_version b/etc/debian_version
index 9d5e716..2f52450 100644
--- a/etc/debian_version
+++ b/etc/debian_version
@@ -1 +1 @@
-9.7
+10.0
diff --git a/etc/issue b/etc/issue
index 6c3dc4f..0d266a6 100644
--- a/etc/issue
+++ b/etc/issue
@@ -1,2 +1,2 @@
-Mendel #OSNAME# (chef) \n \l
+Mendel #OSNAME# (day) \n \l
 
diff --git a/etc/issue.net b/etc/issue.net
index ee883f8..083a488 100644
--- a/etc/issue.net
+++ b/etc/issue.net
@@ -1 +1 @@
-Mendel #OSNAME# (chef)
+Mendel #OSNAME# (day)
diff --git a/etc/lsb-release b/etc/lsb-release
index 6c17bc9..533f2a7 100644
--- a/etc/lsb-release
+++ b/etc/lsb-release
@@ -1,7 +1,7 @@
-DISTRIB_CODENAME=chef
-DISTRIB_DESCRIPTION="Mendel GNU/Linux Chef"
+DISTRIB_CODENAME=day
+DISTRIB_DESCRIPTION="Mendel GNU/Linux Day"
 DISTRIB_ID=Mendel
-DISTRIB_RELEASE=mendel-chef
+DISTRIB_RELEASE=mendel-day
 PRETTY_NAME="Mendel"
 NAME="Mendel"
 ID=Mendel
diff --git a/etc/mendel_version b/etc/mendel_version
index 8c50098..5186d07 100644
--- a/etc/mendel_version
+++ b/etc/mendel_version
@@ -1 +1 @@
-3.1
+4.0
diff --git a/etc/os-release b/etc/os-release
index e91dfcc..d052fbf 100644
--- a/etc/os-release
+++ b/etc/os-release
@@ -1,9 +1,8 @@
-PRETTY_NAME="Mendel #OSNAME# 3 (Chef)"
+PRETTY_NAME="Mendel #OSNAME# 4 (Day)"
 NAME="Mendel #OSNAME#"
-VERSION_ID="3"
-VERSION="3 (chef)"
 ID=mendel
 ID_LIKE=debian
 HOME_URL="https://coral.withgoogle.com/"
 SUPPORT_URL="https://coral.withgoogle.com/"
 BUG_REPORT_URL="https://coral.withgoogle.com/"
+VERSION_CODENAME="day"
diff --git a/licenses/CC0-1.0 b/licenses/CC0-1.0
new file mode 100644
index 0000000..0e259d4
--- /dev/null
+++ b/licenses/CC0-1.0
@@ -0,0 +1,121 @@
+Creative Commons Legal Code
+
+CC0 1.0 Universal
+
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