diff --git a/src/main.rs b/src/main.rs
index a74af38..beb2537 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -14,6 +14,8 @@ use numa::ctx::{handle_query, ServerCtx};
 use numa::forward::Upstream;
 use numa::override_store::OverrideStore;
 use numa::query_log::QueryLog;
+
+const DOH_FALLBACK: &str = "https://9.9.9.9/dns-query";
 use numa::service_store::ServiceStore;
 use numa::stats::ServerStats;
 use numa::system_dns::{
@@ -126,7 +128,7 @@ async fn main() -> numa::Result<()> {
                     .use_rustls_tls()
                     .build()
                     .unwrap_or_default();
-                let url = "https://9.9.9.9/dns-query".to_string();
+                let url = DOH_FALLBACK.to_string();
                 let label = url.clone();
                 (
                     numa::config::UpstreamMode::Forward,
@@ -152,7 +154,7 @@ async fn main() -> numa::Result<()> {
                     .or_else(numa::system_dns::detect_dhcp_dns)
                     .unwrap_or_else(|| {
                         info!("could not detect system DNS, falling back to Quad9 DoH");
-                        "https://9.9.9.9/dns-query".to_string()
+                        DOH_FALLBACK.to_string()
                     })
             } else {
                 config.upstream.address.clone()