diff --git a/mendel.list.template b/mendel.list.template
index ec3662a..21ad31f 100644
--- a/mendel.list.template
+++ b/mendel.list.template
@@ -1,4 +1,4 @@
-deb [arch=armhf,arm64 trusted=yes] https://packages.cloud.google.com/apt mendel-chef main
-deb-src [trusted=yes] https://packages.cloud.google.com/apt mendel-chef main
-deb [arch=armhf,arm64 trusted=yes] https://packages.cloud.google.com/apt mendel-bsp-%BOARDNAME%-chef main
-deb-src [trusted=yes] https://packages.cloud.google.com/apt mendel-bsp-%BOARDNAME%-chef main
+deb [arch=armhf,arm64 trusted=yes] https://packages.cloud.google.com/apt mendel-day main
+deb-src [trusted=yes] https://packages.cloud.google.com/apt mendel-day main
+deb [arch=armhf,arm64 trusted=yes] https://packages.cloud.google.com/apt mendel-bsp-%BOARDNAME%-day main
+deb-src [trusted=yes] https://packages.cloud.google.com/apt mendel-bsp-%BOARDNAME%-day main
diff --git a/packages.mk b/packages.mk
index 11ceaf0..af655b0 100644
--- a/packages.mk
+++ b/packages.mk
@@ -28,8 +28,8 @@
 	mkdir -p $(ROOTDIR)/cache
 	sudo pbuilder create \
 		--basetgz $@ \
-		--othermirror "deb http://packages.cloud.google.com/apt mendel-chef main|deb http://packages.cloud.google.com/apt mendel-bsp-$(BOARD_NAME)-chef main" \
-		--distribution stretch \
+		--othermirror "deb http://packages.cloud.google.com/apt mendel-day main|deb http://packages.cloud.google.com/apt mendel-bsp-$(BOARD_NAME)-day main" \
+		--distribution buster \
 		--architecture amd64 \
 		--extrapackages "crossbuild-essential-armhf crossbuild-essential-arm64 debhelper gnupg lintian"
 	mkdir -p $(ROOTDIR)/cache/base-tmp
diff --git a/pbuilderrc b/pbuilderrc
index ac54eda..7f694e3 100644
--- a/pbuilderrc
+++ b/pbuilderrc
@@ -4,7 +4,7 @@
 # the default template
 #
 # read pbuilderrc.5 document for notes on specific options.
-OTHERMIRROR="deb https://packages.cloud.google.com/apt mendel-chef main|deb https://packages.cloud.google.com/apt mendel-bsp-$BOARD_NAME-chef main"
+OTHERMIRROR="deb https://packages.cloud.google.com/apt mendel-day main|deb https://packages.cloud.google.com/apt mendel-bsp-$BOARD_NAME-day main"
 PBUILDERSATISFYDEPENDSCMD=/usr/lib/pbuilder/pbuilder-satisfydepends-apt
 export DEPSBASE=$PRODUCT_OUT/packages
 BINDMOUNTS="$DEPSBASE $ROOTDIR"
diff --git a/prereqs.mk b/prereqs.mk
index c6c7397..51f56f7 100644
--- a/prereqs.mk
+++ b/prereqs.mk
@@ -22,19 +22,20 @@
 	apt-transport-https \
 	apt-utils \
 	bc \
+	binfmt-support \
 	binutils-aarch64-linux-gnu \
 	build-essential \
-	binfmt-support \
 	ca-certificates \
 	cdbs \
-	crossbuild-essential-arm64 \
-	crossbuild-essential-armhf \
 	coreutils \
 	cpio \
+	crossbuild-essential-arm64 \
+	crossbuild-essential-armhf \
 	curl \
 	debhelper \
 	debian-archive-keyring \
 	device-tree-compiler \
+	dh-python \
 	fakeroot \
 	genext2fs \
 	git \
@@ -50,6 +51,7 @@
 	python-minimal \
 	python2.7 \
 	python3 \
+	python3-all \
 	python3-apt \
 	python3-debian \
 	python3-git \
diff --git a/rootfs.mk b/rootfs.mk
index f394273..62a7328 100644
--- a/rootfs.mk
+++ b/rootfs.mk
@@ -136,8 +136,8 @@
 	sudo tar -xvf $(ROOTDIR)/cache/packages.tgz -C $(ROOTFS_DIR)/opt/aiy/
 endif
 
-	echo 'deb https://deb.debian.org/debian-security/ stretch/updates main' |sudo tee $(ROOTFS_DIR)/etc/apt/sources.list.d/security.list
-	echo 'deb-src https://deb.debian.org/debian-security/ stretch/updates main' |sudo tee -a $(ROOTFS_DIR)/etc/apt/sources.list.d/security.list
+	echo 'deb https://deb.debian.org/debian-security/ buster/updates main' |sudo tee $(ROOTFS_DIR)/etc/apt/sources.list.d/security.list
+	echo 'deb-src https://deb.debian.org/debian-security/ buster/updates main' |sudo tee -a $(ROOTFS_DIR)/etc/apt/sources.list.d/security.list
 	sudo cp $(ROOTDIR)/build/99network-settings $(ROOTFS_DIR)/etc/apt/apt.conf.d/
 	sudo chroot $(ROOTFS_DIR) bash -c 'apt-get update'
 	sudo chroot $(ROOTFS_DIR) bash -c 'apt-get install -y --allow-unauthenticated mendel-keyring'