diff --git a/scripts/ubuntu_20.04_install_map.sh b/scripts/ubuntu_20.04_install_map.sh
index 2a9b2803..746e733e 100755
--- a/scripts/ubuntu_20.04_install_map.sh
+++ b/scripts/ubuntu_20.04_install_map.sh
@@ -5,6 +5,8 @@
 set -x
 set -e
 
+# Update if we haven't updated in the last day.
+[ -z "$(find -H /var/lib/apt/lists -maxdepth 0 -mtime -1)" ] && apt update
 # Install map dependencies.
 apt install -y libboost-all-dev git tar unzip wget bzip2 build-essential autoconf libtool libxml2-dev libgeos-dev \
   libgeos++-dev libpq-dev libbz2-dev libproj-dev munin-node munin protobuf-c-compiler libfreetype6-dev libtiff5-dev \