diff --git a/Dockerfile b/Dockerfile
index 4c11b0c..a28504c 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -59,8 +59,8 @@ ARG GRAV_SUBDIR=html
 WORKDIR /var/www
 RUN curl -o grav-admin.zip -SL https://getgrav.org/download/core/grav-admin/${GRAV_VERSION} && \
     unzip grav-admin.zip && \
-    mkdir -pv ${GRAV_SUBDIR%/*} && \
-    mv -Tv /var/www/grav-admin "var/www/$GRAV_SUBDIR" && \
+    mkdir -pv "${GRAV_SUBDIR}" && \
+    mv -Tv /var/www/grav-admin "var/www/${GRAV_SUBDIR}" && \
     rm -v grav-admin.zip
 
 # Create cron job for Grav maintenance scripts