diff --git a/CHANGELOG.md b/CHANGELOG.md
index a75a9a4..09b4c15 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,11 @@
 CHANGELOG
 =========
 
+v0.53a (May 8, 2021)
+--------------------
+
+The download URL for Z-Push has been revised becaue the old URL stopped working.
+
 v0.53 (April 12, 2021)
 ----------------------
 
diff --git a/README.md b/README.md
index 2813ed7..e08312f 100644
--- a/README.md
+++ b/README.md
@@ -58,7 +58,7 @@ Clone this repository and checkout the tag corresponding to the most recent rele
 
 	$ git clone https://github.com/mail-in-a-box/mailinabox
 	$ cd mailinabox
-	$ git checkout v0.53
+	$ git checkout v0.53a
 
 Begin the installation.
 
diff --git a/setup/bootstrap.sh b/setup/bootstrap.sh
index d804cad..80ea207 100644
--- a/setup/bootstrap.sh
+++ b/setup/bootstrap.sh
@@ -20,7 +20,7 @@ if [ -z "$TAG" ]; then
 	# want to display in status checks.
 	if [ "`lsb_release -d | sed 's/.*:\s*//' | sed 's/18\.04\.[0-9]/18.04/' `" == "Ubuntu 18.04 LTS" ]; then
 		# This machine is running Ubuntu 18.04.
-		TAG=v0.53
+		TAG=v0.53a
 
 	elif [ "`lsb_release -d | sed 's/.*:\s*//' | sed 's/14\.04\.[0-9]/14.04/' `" == "Ubuntu 14.04 LTS" ]; then
 		# This machine is running Ubuntu 14.04.