diff --git a/docker/2_buildpy/build.sh b/docker/2_buildpy/build.sh
index 9766e22..61dd5f0 100755
--- a/docker/2_buildpy/build.sh
+++ b/docker/2_buildpy/build.sh
@@ -18,7 +18,7 @@ echo "Python will be built to $PYTHONTARGET"
 docker build -t pillar_build -f buildpy.docker .
 
 # Use the docker image to build Python 3.6 and mod-wsgi
-GID=$(id --group)
+GID=$(id -g)
 docker run --rm -i \
     -v "$PYTHONTARGET:/opt/python" \
     pillar_build <<EOT
diff --git a/docker/3_buildwheels/build.sh b/docker/3_buildwheels/build.sh
index b48e400..7875b2f 100755
--- a/docker/3_buildwheels/build.sh
+++ b/docker/3_buildwheels/build.sh
@@ -24,7 +24,7 @@ mkdir -p "$WHEELHOUSE"
 
 docker build -t pillar_wheelbuilder -f build.docker .
 
-GID=$(id --group)
+GID=$(id -g)
 docker run --rm -i \
     -v "$WHEELHOUSE:/data/wheelhouse" \
     -v "$TOPDEVDIR:/data/topdev" \