diff --git a/Dockerfile b/Dockerfile
index 5ca374c..8abbc73 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -9,6 +9,7 @@ RUN apt-get update && \
     userdel -r node && \
     useradd -u 1000 -ms /bin/bash tt && \
     useradd -u 1001 -ms /bin/bash student && \
+    usermod -aG student tt && \
     echo "student ALL=(tt) NOPASSWD:/usr/local/bin/joj3\nstudent ALL=(tt) NOPASSWD:/usr/local/bin/joj3-teapot" > /etc/sudoers.d/joj
 
 # install joint-teapot