diff --git a/travis/macos-install.sh b/travis/macos-install.sh
index 3ffea03..51dd1ac 100755
--- a/travis/macos-install.sh
+++ b/travis/macos-install.sh
@@ -2,6 +2,7 @@
 
 set -ex
 
+brew update
 brew install python3
 which python3
 python3 --version