diff --git a/sh/debian.sh b/sh/debian.sh
index feeb8ac..4485be6 100644
--- a/sh/debian.sh
+++ b/sh/debian.sh
@@ -64,7 +64,7 @@ apt_update() {
 		update
 }
 
-apt_upgrade() {
+sh_apt_upgrade() {
 	apt-get \
 		upgrade \
 		--assume-yes
diff --git a/sh/rescue/common.sh b/sh/rescue/common.sh
index 69aded0..a9a08d7 100644
--- a/sh/rescue/common.sh
+++ b/sh/rescue/common.sh
@@ -34,7 +34,7 @@ rescue_install() {
 	# disable frontend
 	sh_debian_frontend_disable
 	# upgrade packages
-	apt_upgrade
+	sh_apt_upgrade
 	# install packages
 	apt_install_release \
 		"man-db" \