diff --git a/lib/sourcemaps.js b/lib/sourcemaps.js
index <HASH>..<HASH> 100644
--- a/lib/sourcemaps.js
+++ b/lib/sourcemaps.js
@@ -23,7 +23,12 @@ function getMapObject(map) {
   }
 }
 
-exports.concatenateSourceMaps = function(sourceFilename, mapsWithOffsets, sourceRoot) {
+exports.concatenateSourceMaps = function(sourceFilename, mapsWithOffsets, sourceRoot, includeSourcesContent) {
+  if (includeSourcesContent) {
+    console.log('WARNING: `includeSourcesContent` not support yet, ' +
+                'see https://github.com/systemjs/builder/issues/68');
+  }
+
   var generated = new sourceMap.SourceMapGenerator({
     file: sourceFilename
   });
Output warning re: `includeSourcesContent` not being supported yet