diff --git a/scripts/install.sh b/scripts/install.sh
index 10b9f581..19ffd2bf 100644
--- a/scripts/install.sh
+++ b/scripts/install.sh
@@ -191,10 +191,10 @@ install_cuda_driver_apt() {
     case $1 in
         debian)
             status 'Enabling contrib sources...'
-            $SUDO sed 's/main/contrib/' < /etc/apt/sources.list | $SUDO tee /etc/apt/sources.list.d/contrib.list > /dev/null
-            if [ -f "/etc/apt/sources.list.d/debian.sources" ]; then
-                $SUDO sed 's/main/contrib/' < /etc/apt/sources.list.d/debian.sources | $SUDO tee /etc/apt/sources.list.d/contrib.sources > /dev/null
-            fi
+            [ -f "/etc/apt/sources.list.d/debian.sources" ] \
+                && SOURCES_LIST="/etc/apt/sources.list.d/debian.sources" \
+                || SOURCES_LIST="/etc/apt/sources.list"
+            sed 's/main/contrib/' <"$SOURCES_LIST" | $SUDO tee /etc/apt/sources.list.d/contrib.sources >/dev/null
             ;;
     esac