diff --git a/src/travis/osx-x86_64-install.sh b/src/travis/osx-x86_64-install.sh
index 0ac11a04..22d32d3c 100755
--- a/src/travis/osx-x86_64-install.sh
+++ b/src/travis/osx-x86_64-install.sh
@@ -1,5 +1,5 @@
 cd src
-pyinstaller --clean --debug -F --distpath=gam $GAMOS-gam.spec
+$python -OO -m PyInstaller --clean --debug -F --distpath=gam $GAMOS-gam.spec
 gam/gam version
 export GAMVERSION=`gam/gam version simple`
 cp LICENSE gam