diff --git a/src/src.pro b/src/src.pro
index d44ddf020..72ea00840 100644
--- a/src/src.pro
+++ b/src/src.pro
@@ -40,7 +40,7 @@ CONFIG(debug, debug|release):message(Project is built in DEBUG mode.)
 CONFIG(release, debug|release):message(Project is built in RELEASE mode.)
 
 # Disable debug output in release mode
-!debug {
+CONFIG(release, debug|release) {
    message(Disabling debug output.)
    DEFINES += QT_NO_DEBUG_OUTPUT
 }
diff --git a/winconf.pri b/winconf.pri
index 546b1a1e9..af58f5b19 100644
--- a/winconf.pri
+++ b/winconf.pri
@@ -27,7 +27,7 @@ DEFINES += _WIN32_WINNT=0x0500
 DEFINES += __USE_W32_SOCKETS
 DEFINES += WITH_SHIPPED_GEOIP_H
 
-debug {
+CONFIG(debug, debug|release) {
   DEFINES += TORRENT_DEBUG
 } else {
   DEFINES += NDEBUG
@@ -35,7 +35,7 @@ debug {
 
 RC_FILE = qbittorrent.rc
 
-debug {
+CONFIG(debug, debug|release) {
   LIBS += libtorrentd.lib \
           libboost_system-vc90-mt-gd.lib \
           libboost_filesystem-vc90-mt-gd.lib \