[#7976] concat sourcemaps together properly
diff --git a/Brocfile.js b/Brocfile.js
index 93cab0b..71a8f90 100644
--- a/Brocfile.js
+++ b/Brocfile.js
@@ -17,8 +17,7 @@
        under the License.
 */
 var babelTranspiler = require("broccoli-babel-transpiler");
-var sourceMap = require('broccoli-source-map');
-var concat = require('broccoli-concat');
+var sourceMapConcat = require('broccoli-sourcemap-concat');
 var funnel = require('broccoli-funnel');
 var uglifyJavaScript = require('broccoli-uglify-js');
 
@@ -31,11 +30,10 @@
     sourceMaps: 'inline',  // external doesn't work, have to use extract below
     comments: false,
 });
-tree = concat(tree, {
-  inputFiles: ['**/*.js'],
+tree = sourceMapConcat(tree, {
+  inputFiles: ['**/*'],
   outputFile: '/transpiled.js'
 });
-tree = sourceMap.extract(tree);
 
 if (process.env.BROCCOLI_ENV === 'production') {
     /* can't use this for dev mode, since it drops the sourcemap comment even if we set  output: {comments: true}
diff --git a/package.json b/package.json
index 95fa5ac..f850f00 100644
--- a/package.json
+++ b/package.json
@@ -17,9 +17,8 @@
   "devDependencies": {
     "broccoli": "^0.16.8",
     "broccoli-babel-transpiler": "^5.4.5",
-    "broccoli-concat": "0.0.13",
     "broccoli-funnel": "^0.2.8",
-    "broccoli-source-map": "^0.2.3",
+    "broccoli-sourcemap-concat": "^2.0.1",
     "broccoli-uglify-js": "^0.1.3"
   }
 }