diff --git a/travis/macos-install.sh b/travis/macos-install.sh
index 51dd1ac..2da30ef 100755
--- a/travis/macos-install.sh
+++ b/travis/macos-install.sh
@@ -2,8 +2,9 @@
 
 set -ex
 
+export HOMEBREW_NO_INSTALL_CLEANUP=1
 brew update
-brew install python3
+brew upgrade python
 which python3
 python3 --version
 which pip3