diff --git a/repo2docker/buildpacks/base.py b/repo2docker/buildpacks/base.py
index ece81745..e3a570f0 100644
--- a/repo2docker/buildpacks/base.py
+++ b/repo2docker/buildpacks/base.py
@@ -44,7 +44,7 @@ ENV HOME /home/${NB_USER}
 
 RUN groupadd \
         --gid ${NB_UID} \
-        ${NB_USER} &&
+        ${NB_USER} && \
     useradd \
         --comment "Default user" \
         --create-home \