diff --git a/scripts/upgrade b/scripts/upgrade
index 6265efe..2228834 100644
--- a/scripts/upgrade
+++ b/scripts/upgrade
@@ -17,17 +17,17 @@ systemctl stop jellyfin
 # DOWNLOAD, CHECK AND UNPACK SOURCE
 #=================================================
 
-ynh_app_setting_set $app final_path $final_path
+ynh_app_setting_set "$app" final_path "$final_path"
 
 # Download, check integrity, uncompress and patch the source from jellyfin-ffmpeg-[arch].src
-case `uname -m` in
+case $(uname -m) in
     x86_64) ynh_setup_source "$final_path" "jellyfin-ffmpeg-amd64" ;;
     aarch64) ynh_setup_source "$final_path" "jellyfin-ffmpeg-arm64" ;;
     *) ynh_die "Unknown arch" ;;
 esac
 
 # Download, check integrity, uncompress and patch the source from jellyfin-[arch].src
-case `uname -m` in
+case $(uname -m) in
     x86_64) ynh_setup_source "$final_path" "jellyfin-amd64" ;;
     aarch64) ynh_setup_source "$final_path" "jellyfin-arm64" ;;
     *) ynh_die "Unknown arch" ;;
@@ -40,9 +40,9 @@ ynh_setup_source "$final_path" "jellyfin-plugin-ldapauth"
 # INSTALL JELLYFIN
 #==============================================
 
-dpkg --install $final_path/jellyfin-ffmpeg.deb
-dpkg --install $final_path/jellyfin.deb
-rm $final_path/*.deb
+dpkg --install "$final_path"/jellyfin-ffmpeg.deb
+dpkg --install "$final_path"/jellyfin.deb
+rm "$final_path"/*.deb
 
 #=================================================
 # NGINX CONFIGURATION
@@ -70,4 +70,3 @@ rm $final_path/*.deb
 
 # Start jellyfin service
 systemctl start jellyfin
-