diff --git a/root/etc/s6-overlay/s6-rc.d/init-wireguard-confs/run b/root/etc/s6-overlay/s6-rc.d/init-wireguard-confs/run
index 36bb2aa..a3ee264 100755
--- a/root/etc/s6-overlay/s6-rc.d/init-wireguard-confs/run
+++ b/root/etc/s6-overlay/s6-rc.d/init-wireguard-confs/run
@@ -184,7 +184,8 @@ else
         echo "**** No client conf found. Provide your own client conf as \"/config/wg0.conf\" and restart the container. ****"
         sleep infinity
     fi
-    printf %s "${USE_COREDNS,,:-false}" > /run/s6/container_environment/USE_COREDNS
+    USE_COREDNS="${USE_COREDNS,,}"
+    printf %s "${USE_COREDNS:-false}" > /run/s6/container_environment/USE_COREDNS
 fi
 
 # set up CoreDNS