diff --git a/configure b/configure
index f726cf4bc..44eb92cdb 100755
--- a/configure
+++ b/configure
@@ -625,7 +625,7 @@ public:
                 s = conf->getenv("QC_WITH_QTSINGLEAPPLICATION");
                 if(s.compare("system", Qt::CaseInsensitive) == 0) {
                   // System
-                  conf->addDefine("USE_SYSTEM_QTSINGLEAPPLICATION");
+                  conf->addExtra("CONFIG += usesystemqtsingleapplication");
                   printf(" [system] ");
                 } else {
                   printf(" [shipped] ");
diff --git a/qcm/qtsingleapplication.qcm b/qcm/qtsingleapplication.qcm
index 92299bf64..548671492 100644
--- a/qcm/qtsingleapplication.qcm
+++ b/qcm/qtsingleapplication.qcm
@@ -16,7 +16,7 @@ public:
                 s = conf->getenv("QC_WITH_QTSINGLEAPPLICATION");
                 if(s.compare("system", Qt::CaseInsensitive) == 0) {
                   // System
-                  conf->addDefine("USE_SYSTEM_QTSINGLEAPPLICATION");
+                  conf->addExtra("CONFIG += usesystemqtsingleapplication");
                   printf(" [system] ");
                 } else {
                   printf(" [shipped] ");
diff --git a/src/src.pro b/src/src.pro
index ced044bfa..47fac9c58 100644
--- a/src/src.pro
+++ b/src/src.pro
@@ -65,7 +65,7 @@ RESOURCES += icons.qrc \
             about.qrc
 
 # Source code
-contains(DEFINES, USE_SYSTEM_QTSINGLEAPPLICATION) {
+usesystemqtsingleapplication {
   nox {
     CONFIG += qtsinglecoreapplication
   } else {