diff --git a/rbutil/rbutilqt/Makefile.libs b/rbutil/rbutilqt/Makefile.libs
index 24fe85e269..6d5c8c5354 100644
--- a/rbutil/rbutilqt/Makefile.libs
+++ b/rbutil/rbutilqt/Makefile.libs
@@ -28,6 +28,7 @@ export SYS_SPEEX
 export TARGET_DIR
 export RBBASE_DIR
 export CFLAGS=$(EXTRALIB_CFLAGS)
+export CXXFLAGS=$(EXTRALIB_CXXFLAGS)
 export CC=$(EXTRALIBS_CC)
 export CXX=$(EXTRALIBS_CXX)
 export AR=$(EXTRALIBS_AR)
diff --git a/rbutil/rbutilqt/rbutilqt.pro b/rbutil/rbutilqt/rbutilqt.pro
index a845c3ca36..f51d3608b3 100644
--- a/rbutil/rbutilqt/rbutilqt.pro
+++ b/rbutil/rbutilqt/rbutilqt.pro
@@ -33,7 +33,8 @@ unix:!mac:!noccache {
 MACHINEFLAGS = $$find(QMAKE_CFLAGS, -m[63][42])
 EXTRALIBS_OPTS += EXTRALIBS_CC=\"$$QMAKE_CC\"
 EXTRALIBS_OPTS += EXTRALIBS_CXX=\"$$QMAKE_CXX\"
-EXTRALIBS_OPTS += EXTRALIB_CFLAGS=\"$$MACHINEFLAGS\" \
+EXTRALIBS_OPTS += EXTRALIB_CFLAGS=\"$$MACHINEFLAGS\"
+EXTRALIBS_OPTS += EXTRALIB_CXXFLAGS=\"$$MACHINEFLAGS\"
 
 MYBUILDDIR = $$OUT_PWD/build/
 MYLIBBUILDDIR = $$MYBUILDDIR/libs/