diff --git a/servers/puppet/modules/humbug/files/nginx/sites-available/humbug b/servers/puppet/modules/humbug/files/nginx/sites-available/humbug
index 80b9611cd9..161b63a37e 100644
--- a/servers/puppet/modules/humbug/files/nginx/sites-available/humbug
+++ b/servers/puppet/modules/humbug/files/nginx/sites-available/humbug
@@ -39,7 +39,9 @@ server {
     ssl_certificate /etc/ssl/certs/wildcard-humbughq.com.combined-chain.crt;
     ssl_certificate_key /etc/ssl/private/app.humbughq.com.key;
 
-    server_name humbughq.com www.humbughq.com;
+    # We don't actually have an SSL cert for zulip.com, but that's okay since
+    # clients will never be accessing this host directly.
+    server_name humbughq.com www.humbughq.com zulip.com;
 
     # Avoid clickjacking attacks
     add_header X-Frame-Options DENY;