diff --git a/debian/postinst b/debian/postinst
index 6ab14fa..026b12f 100644
--- a/debian/postinst
+++ b/debian/postinst
@@ -10,3 +10,5 @@ case "$1" in
 esac
 
 #DEBHELPER#
+
+exit 0
diff --git a/debian/preinst b/debian/preinst
index 7d9c403..cb117a0 100644
--- a/debian/preinst
+++ b/debian/preinst
@@ -2,10 +2,11 @@
 
 set -e
 
-if [ "$1" = upgrade ]; then
-
-    [ -f /usr/bin/startlxqt ] && update-alternatives --remove x-window-manager /usr/bin/startlxqt
-fi
+case "$1" in
+    upgrade)
+        [ -f /usr/bin/startlxqt ] && update-alternatives --remove x-window-manager /usr/bin/startlxqt
+        ;;
+esac
 
 #DEBHELPER#
 
diff --git a/debian/prerm b/debian/prerm
index 0d3a275..55977eb 100644
--- a/debian/prerm
+++ b/debian/prerm
@@ -9,3 +9,5 @@ case "$1" in
 esac
 
 #DEBHELPER#
+
+exit 0