diff --git a/packages/runtimes/hmr/src/HMRRuntime.js b/packages/runtimes/hmr/src/HMRRuntime.js
index d02a11b5803..93295befae0 100644
--- a/packages/runtimes/hmr/src/HMRRuntime.js
+++ b/packages/runtimes/hmr/src/HMRRuntime.js
@@ -21,7 +21,14 @@ export default (new Runtime({
       filePath: __filename,
       code:
         `var HMR_HOST = ${JSON.stringify(host != null ? host : null)};` +
-        `var HMR_PORT = ${JSON.stringify(port != null ? port : null)};` +
+        `var HMR_PORT = ${JSON.stringify(
+          port != null &&
+            // Default to the HTTP port in the browser, only override
+            // in watch mode or if hmr port != serve port
+            (!options.serveOptions || options.serveOptions.port !== port)
+            ? port
+            : null,
+        )};` +
         `var HMR_SECURE = ${JSON.stringify(
           !!(options.serveOptions && options.serveOptions.https),
         )};` +