diff --git a/lib/npm-file-manager.js b/lib/npm-file-manager.js
index 0eb44a8..628b687 100644
--- a/lib/npm-file-manager.js
+++ b/lib/npm-file-manager.js
@@ -47,28 +47,33 @@ module.exports = function(less) {
         });
     };
 
-    NpmFileManager.prototype.loadFile = function(filename, currentDirectory, options, environment) {
+    NpmFileManager.prototype.loadFile = function(filename, currentDirectory, options, environment, callback) {
+        options = options || {};
         try {
             filename = this.resolve(filename, currentDirectory);
         }
         catch(e) {
+            if (options.syncImport) {
+                callback(e);
+                return;
+            }
             return new PromiseConstructor(
                 function(fullfill, reject) {
                     reject(e);
                 }
             );
         }
-        return FileManager.prototype.loadFile.call(this, filename, "", options, environment);
+        return FileManager.prototype.loadFile.call(this, filename, "", options, environment, callback);
     };
 
-    NpmFileManager.prototype.loadFileSync = function(filename, currentDirectory, options, environment) {
+    NpmFileManager.prototype.loadFileSync = function(filename, currentDirectory, options, environment, encoding) {
         try {
             filename = this.resolve(filename, currentDirectory);
         }
         catch(e) {
             return { error: e };
         }
-        return FileManager.prototype.loadFileSync.call(this, filename, "", options, environment);
+        return FileManager.prototype.loadFileSync.call(this, filename, "", options, environment, encoding);
     };
 
     NpmFileManager.prototype.tryAppendExtension = function(path, ext) {