diff --git a/Dockerfile b/Dockerfile
index 1570b4a..8a38241 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,4 +1,4 @@
-FROM lsiobase/alpine.$IMAGE_ARCH:3.9
+FROM lsiobase/alpine.${IMAGE_ARCH}:3.9
 
 ENV PUID=1000
 ENV PGID=1000