diff --git a/sled-agent/src/illumos/running_zone.rs b/sled-agent/src/illumos/running_zone.rs
index a58b4c9d18..fee2318768 100644
--- a/sled-agent/src/illumos/running_zone.rs
+++ b/sled-agent/src/illumos/running_zone.rs
@@ -11,6 +11,7 @@ use crate::illumos::zone::{AddressRequest, ZONE_PREFIX};
 use crate::opte::OptePort;
 use ipnetwork::IpNetwork;
 use slog::Logger;
+use std::net::Ipv6Addr;
 use std::path::PathBuf;
 
 #[cfg(test)]
@@ -171,17 +172,17 @@ impl RunningZone {
         Ok(network)
     }
 
-    pub async fn add_route(
+    pub async fn add_default_route(
         &self,
-        destination: ipnetwork::Ipv6Network,
+        gateway: Ipv6Addr,
     ) -> Result<(), RunCommandError> {
         self.run_cmd(&[
             "/usr/sbin/route",
             "add",
             "-inet6",
-            &format!("{}/{}", destination.network(), destination.prefix()),
+            "default",
             "-inet6",
-            &destination.ip().to_string(),
+            &gateway.to_string(),
         ])?;
         Ok(())
     }
diff --git a/sled-agent/src/services.rs b/sled-agent/src/services.rs
index aafd89b221..72444a79b1 100644
--- a/sled-agent/src/services.rs
+++ b/sled-agent/src/services.rs
@@ -10,8 +10,7 @@ use crate::illumos::vnic::VnicAllocator;
 use crate::illumos::zone::AddressRequest;
 use crate::params::{ServiceEnsureBody, ServiceRequest};
 use crate::zone::Zones;
-use ipnetwork::Ipv6Network;
-use omicron_common::address::{AZ_PREFIX, DNS_PORT, DNS_SERVER_PORT};
+use omicron_common::address::{DNS_PORT, DNS_SERVER_PORT};
 use slog::Logger;
 use std::collections::HashSet;
 use std::iter::FromIterator;
@@ -229,7 +228,7 @@ impl ServiceManager {
                 })?;
             }
 
-            let gz_route_subnet = if !service.gz_addresses.is_empty() {
+            let gateway = if !service.gz_addresses.is_empty() {
                 // If this service supplies its own GZ address, add a route.
                 //
                 // This is currently being used for the DNS service.
@@ -238,16 +237,18 @@ impl ServiceManager {
                 // can be supplied - now that we're actively using it, we
                 // aren't really handling the "many GZ addresses" case, and it
                 // doesn't seem necessary now.
-                Ipv6Network::new(service.gz_addresses[0], AZ_PREFIX).unwrap()
+                service.gz_addresses[0]
             } else {
-                // Otherwise, add a route to the global Zone's sled address for
-                // everything within the AZ.
-                Ipv6Network::new(self.underlay_address, AZ_PREFIX).unwrap()
+                self.underlay_address
             };
-            running_zone.add_route(gz_route_subnet).await.map_err(|err| {
+
+            running_zone.add_default_route(gateway).await.map_err(|err| {
                 Error::ZoneCommand { intent: "Adding Route".to_string(), err }
             })?;
 
+            // TODO: Related to
+            // https://github.com/oxidecomputer/omicron/pull/1124 , should we
+            // avoid importing this manifest?
             debug!(self.log, "importing manifest");
 
             running_zone
diff --git a/sled-agent/src/storage_manager.rs b/sled-agent/src/storage_manager.rs
index ee364b4031..a02e68baae 100644
--- a/sled-agent/src/storage_manager.rs
+++ b/sled-agent/src/storage_manager.rs
@@ -15,9 +15,7 @@ use crate::params::DatasetKind;
 use futures::stream::FuturesOrdered;
 use futures::FutureExt;
 use futures::StreamExt;
-use ipnetwork::Ipv6Network;
 use nexus_client::types::{DatasetPutRequest, ZpoolPutRequest};
-use omicron_common::address::AZ_PREFIX;
 use omicron_common::api::external::{ByteCount, ByteCountRangeError};
 use omicron_common::backoff;
 use schemars::JsonSchema;
@@ -497,9 +495,10 @@ async fn ensure_running_zone(
 
             zone.ensure_address(address_request).await?;
 
-            let gz_subnet =
-                Ipv6Network::new(underlay_address, AZ_PREFIX).unwrap();
-            zone.add_route(gz_subnet).await.map_err(Error::ZoneCommand)?;
+            let gateway = underlay_address;
+            zone.add_default_route(gateway)
+                .await
+                .map_err(Error::ZoneCommand)?;
 
             dataset_info
                 .start_zone(log, &zone, dataset_info.address, do_format)