diff --git a/index.js b/index.js
index b82001b..bc6f9ae 100644
--- a/index.js
+++ b/index.js
@@ -47,6 +47,7 @@ module.exports = function (params) {
     }
 
     if (file.isBuffer()) {
+      if (!inExtensions(file.path)) return callback(null, file);
       var result = processInclude(String(file.contents), file.path, file.sourceMap);
       file.contents = new Buffer(result.content);