diff --git a/Dockerfile b/Dockerfile
index 71b835b..ca550f0 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -13,7 +13,7 @@ ENV LANG='en_US.UTF-8' \
     PM_GID='1003'
 
 RUN zypper -n in tar wget gzip
-RUN sed -i 's/^CREATE_MAIL_SPOOL=yes/CREATE_MAIL_SPOOL=no/' /etc/default/useradd && \
+RUN /usr/bin/sed -i 's/^CREATE_MAIL_SPOOL=yes/CREATE_MAIL_SPOOL=no/' /etc/default/useradd && \
     /usr/sbin/groupadd -g $PM_GID $PM_GROUP && \
     /usr/sbin/useradd -u $PM_UID -g $PM_GROUP -M $PM_USER && \
     mkdir /pmmp && \