diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 254df9af1..e6d1ef5ff 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -56,6 +56,7 @@ build-and-test:
         paths:
             - build/test/piglit-results/
     variables:
+        LC_ALL: C.UTF-8
         PIGLIT_DIR: /root/piglit
         XTEST_DIR: /root/xts
     script: