diff --git a/lib/core/index.js b/lib/core/index.js
index a3d296ef..d061518f 100644
--- a/lib/core/index.js
+++ b/lib/core/index.js
@@ -200,9 +200,8 @@ module.exports = function createMiddleware(_dir, _options) {
         path.relative(path.join('/', baseDir), pathname)
       )
     );
-    // determine compressed forms if they were to exist, make sure to handle pre-compressed files, i.e. files with .br/.gz extension. we will serve them "as-is"
-    gzippedFile = `${file}.gz`;
-    brotliFile = `${file}.br`;
+    gzippedFile = file.slice(-3) === ".gz" ? file : `${file}.gz`;
+    brotliFile = file.slice(-3) === ".br" ? file : `${file}.br`;
     
     if ( opts.forceContentEncoding ) {
       if ( file.endsWith('.gz') ) gzippedFile = file;