diff --git a/Dockerfile b/Dockerfile
index 0a6ea9c..c0a0dc3 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -12,9 +12,9 @@ EXPOSE 443
 
 WORKDIR /opt/websockify
 
-ENV LOCALPORT=80
-ENV DEST=box.imzadi.de:23
-ENV OPTS=--web /data
+ENV LOCALPORT="80"
+ENV DEST="box.imzadi.de:23"
+ENV OPTS="--web /data"
 
 ENTRYPOINT ["/usr/local/bin/websockify", "$LOCALPORT $DEST $OPTS"]