diff --git a/browser/build.js b/browser/build.js
index 4deae0085..ca91ca638 100644
--- a/browser/build.js
+++ b/browser/build.js
@@ -40,7 +40,9 @@ if (!program.includeall && (!program.submodules || program.submodules.length ===
 }
 
 var pack = function (params) {
-  var preludePath  = 'node_modules/soop/example/custom_prelude.js';
+  var file = require.resolve('soop');
+  var dir = file.substr(0, file.length - String('soop.js').length);
+  var preludePath = dir + 'example/custom_prelude.js';
   params.raw = true;
   params.sourceMapPrefix = '//#';
   params.prelude = fs.readFileSync(preludePath, 'utf8');