diff --git a/.build.sh b/.build.sh
index 97e97bb..bfe7232 100755
--- a/.build.sh
+++ b/.build.sh
@@ -4,7 +4,7 @@
 FROM ubuntu:15.10
 RUN DEBIAN_FRONTEND=noninteractive apt-get update && apt-get upgrade -yy
 RUN DEBIAN_FRONTEND=noninteractive apt-get install --no-install-recommends -yy make g++ gcc libsystemd-dev libc6-dev pkg-config
-RUN groupadd -g ${GROUPS} ${USER} && useradd -d ${HOME} -m -u ${UID} -g ${GROUPS} ${USER}
+RUN groupadd -g ${GROUPS[0]} ${USER} && useradd -d ${HOME} -m -u ${UID} -g ${GROUPS[0]} ${USER}
 USER ${USER}
 ENV HOME ${HOME}
 RUN /bin/bash