diff --git a/src/shadowbox/server/main.ts b/src/shadowbox/server/main.ts
index 40c8a642..2b533ca2 100644
--- a/src/shadowbox/server/main.ts
+++ b/src/shadowbox/server/main.ts
@@ -138,7 +138,9 @@ async function main() {
   logging.info('Starting...');
 
   const prometheusPort = await portProvider.reserveFirstFreePort(9090);
-  const prometheusLocation = `localhost:${prometheusPort}`;
+  // Use 127.0.0.1 instead of localhost for Prometheus because it's resolving incorrectly for some users.
+  // See https://github.com/Jigsaw-Code/outline-server/issues/341
+  const prometheusLocation = `127.0.0.1:${prometheusPort}`;
 
   const nodeMetricsPort = await portProvider.reserveFirstFreePort(prometheusPort + 1);
   exportPrometheusMetrics(prometheus.register, nodeMetricsPort);