diff --git a/build.sh b/build.sh
index d9eb59979..5fc5eff56 100755
--- a/build.sh
+++ b/build.sh
@@ -16,9 +16,9 @@ if [ -d "$VENV" ]; then
   rm -rf "$VENV"
 fi
 virtualenv "$VENV"
-set +e
+set +u
 source "$VENV/bin/activate"
-set -e
+set -u
 
 
 (