diff --git a/package.json b/package.json
index 031e3395..53c2a0d9 100644
--- a/package.json
+++ b/package.json
@@ -16,10 +16,12 @@
     },
     "dependencies": {
         "async"      : "~0.2.6",
-        "source-map" : "~0.1.33",
         "optimist"   : "~0.3.5",
         "uglify-to-browserify": "~1.0.0"
     },
+    "optionalDependencies": {
+        "source-map" : "~0.1.33"
+    },
     "browserify": {
         "transform": [ "uglify-to-browserify" ]
     },