diff --git a/signalk/rootfs/etc/cont-init.d/99-run.sh b/signalk/rootfs/etc/cont-init.d/99-run.sh
index ea5f2fc25..cd3e676a6 100755
--- a/signalk/rootfs/etc/cont-init.d/99-run.sh
+++ b/signalk/rootfs/etc/cont-init.d/99-run.sh
@@ -16,7 +16,7 @@ ln -sf /config/.signalk "/home/node/.signalk"
 # Set single user for ssl files
 for files in ssl-key.pem ssl-cert.pem; do
     if [ -e /config/.signalk/"$files" ]; then
-        chown `${(id -u):}$`(id -g) /config/.signalk/"$files"
+        chown "${(id -u)}:${(id -g)}" /config/.signalk/"$files"
         chmod 600 /config/.signalk/"$files"
     fi
 done