diff --git a/binder/appendix.txt b/binder/appendix.txt
index 18f1699..7b0772d 100644
--- a/binder/appendix.txt
+++ b/binder/appendix.txt
@@ -1,6 +1,6 @@
 USER root
 ENV DEBIAN_FRONTEND=noninteractive
-RUN apt update && \
+RUN apt-get update && \
     wget -q -O /tmp/lrose.deb https://github.com/NCAR/lrose-core/releases/download/lrose-core-20220222/lrose-core-20220222.ubuntu_18.04.amd64.deb && \
     apt-get -y install /tmp/lrose.deb && \
     apt-get clean && \