diff --git a/build-for-mac-os.sh b/build-for-mac-os.sh
index e5192b426..c123cb21e 100755
--- a/build-for-mac-os.sh
+++ b/build-for-mac-os.sh
@@ -23,7 +23,11 @@
   --with-readline=yes \
   --enable-openmp \
   --disable-debug \
-  --prefix=/Applications/ngspice
+  --prefix=/Applications/ngspice \
+  CFLAGS="-O2 -I/opt/X11/include/freetype2" \
+  LDFLAGS="-lomp"
+# The last two lines may depend on the lib installations
+# please check if there are any problems
 
 make -j4
 make DESTDIR="$(pwd)/root-tree" install