diff -Nru a/musique.pro b/musique.pro
--- a/musique.pro	2016-12-12 22:24:11.000000000 +0100
+++ b/musique.pro	2017-01-04 17:59:21.384145360 +0100
@@ -18,7 +18,11 @@
 
 QT += network sql widgets
 
+isEmpty(USE_SYSTEM_QTSINGLEAPPLICATION){
 include(src/qtsingleapplication/qtsingleapplication.pri)
+} else {
+  CONFIG += qtsingleapplication
+}
 include(src/http/http.pri)
 include(src/tags/tags.pri)