diff --git a/.travis.yml b/.travis.yml
index 16c7657..991cbe7 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -13,7 +13,8 @@ cache:
     - "$HOME/.choosenim/toolchains/nim-0.19.2"
 
 install:
-  - set -ue
+  # `set -u` failed for ubuntu: /home/travis/.travis/job_stages: line 107: secure: unbound variable
+  - set -e
   - export CHOOSENIM_CHOOSE_VERSION=$BRANCH
   - |
       curl https://nim-lang.org/choosenim/init.sh -sSf > init.sh