diff --git a/src/headerdef.rs b/src/headerdef.rs
index 1669c91c1..8102bcb81 100644
--- a/src/headerdef.rs
+++ b/src/headerdef.rs
@@ -119,6 +119,11 @@ pub enum HeaderDef {
     AuthenticationResults,
 
     /// Node address from iroh where direct addresses have been removed.
+    ///
+    /// The node address sent in this header must have
+    /// a non-null relay URL as contacting home relay
+    /// is the only way to reach the node without
+    /// direct addresses and global discovery.
     IrohNodeAddr,
 
     /// Advertised gossip topic for one webxdc.
diff --git a/src/mimefactory.rs b/src/mimefactory.rs
index 59da34031..cefab8476 100644
--- a/src/mimefactory.rs
+++ b/src/mimefactory.rs
@@ -1522,16 +1522,19 @@ impl MimeFactory {
                 ));
             }
             SystemMessage::IrohNodeAddr => {
+                let node_addr = context
+                    .get_or_try_init_peer_channel()
+                    .await?
+                    .get_node_addr()
+                    .await?;
+
+                // We should not send `null` as relay URL
+                // as this is the only way to reach the node.
+                debug_assert!(node_addr.relay_url().is_some());
                 headers.push((
                     HeaderDef::IrohNodeAddr.into(),
-                    mail_builder::headers::text::Text::new(serde_json::to_string(
-                        &context
-                            .get_or_try_init_peer_channel()
-                            .await?
-                            .get_node_addr()
-                            .await?,
-                    )?)
-                    .into(),
+                    mail_builder::headers::text::Text::new(serde_json::to_string(&node_addr)?)
+                        .into(),
                 ));
             }
             SystemMessage::CallAccepted => {
diff --git a/src/peer_channels.rs b/src/peer_channels.rs
index 0299affad..c74a4d695 100644
--- a/src/peer_channels.rs
+++ b/src/peer_channels.rs
@@ -185,9 +185,14 @@ impl Iroh {
     }
 
     /// Get the iroh [NodeAddr] without direct IP addresses.
+    ///
+    /// The address is guaranteed to have home relay URL set
+    /// as it is the only way to reach the node
+    /// without global discovery mechanisms.
     pub(crate) async fn get_node_addr(&self) -> Result<NodeAddr> {
         let mut addr = self.router.endpoint().node_addr().await?;
         addr.direct_addresses = BTreeSet::new();
+        debug_assert!(addr.relay_url().is_some());
         Ok(addr)
     }