diff --git a/src/libs/qmljs/qmljs.pro b/src/libs/qmljs/qmljs.pro
index cd3b8fc0bf2..30dfe3d6d96 100644
--- a/src/libs/qmljs/qmljs.pro
+++ b/src/libs/qmljs/qmljs.pro
@@ -3,8 +3,6 @@ CONFIG += dll
 TARGET = QmlJS
 DEFINES += QMLJS_BUILD_DIR QT_CREATOR
 
-unix:QMAKE_CXXFLAGS_DEBUG += -O3
-
 include(../../qtcreatorlibrary.pri)
 include(qmljs-lib.pri)
 include(../utils/utils.pri)