diff --git a/Dockerfile-CI b/Dockerfile-CI
index a105165cc99bcc40834478acd4cf0a5cfab02358..0b7170267c713261787b4e7ebc47d24a82d8fed9 100644
--- a/Dockerfile-CI
+++ b/Dockerfile-CI
@@ -13,3 +13,6 @@ RUN cd /tmp/binder && \
 RUN cp -rav /tmp/binder/install_files/* /opt/conda/
 
 RUN rm -rf /tmp/binder
+
+# Set default language
+ENV LANG fr_FR.UTF-8