diff --git a/.circleci/osx_install_dependencies.sh b/.circleci/osx_install_dependencies.sh
index 978772e19..1ce75c3d5 100755
--- a/.circleci/osx_install_dependencies.sh
+++ b/.circleci/osx_install_dependencies.sh
@@ -33,6 +33,8 @@
 # - /usr/local/Cellar
 # - /usr/local/Homebrew
 
+set -eu
+
 if [ ! -f /usr/local/lib/libz3.a ] # if this file does not exists (cache was not restored), rebuild dependencies
 then
   brew unlink python