--- a/testing/mozharness/configs/repackage/osx_signed.py
+++ b/testing/mozharness/configs/repackage/osx_signed.py
@@ -1,12 +1,11 @@
 import os
 
 config = {
-    "signed_input": os.environ['SIGNED_INPUT'],  # Required Env Var
     "input_filename": "target.tar.gz",
     "output_filename": "target.dmg",
     "input_home": "/home/worker/workspace/inputs",
 
     # ToolTool
     "tooltool_manifest_src": 'browser/config/tooltool-manifests/macosx64/cross-releng.manifest',
     "tooltool_url": 'http://relengapi/tooltool/',
     "tooltool_bootstrap": "setup.sh",

--- a/testing/mozharness/scripts/repackage.py
+++ b/testing/mozharness/scripts/repackage.py
@@ -9,16 +9,17 @@ from mozharness.mozilla.mock import ERRO
 
 class Repackage(BaseScript):
 
     config_options = [[
         ['--signed-input', ],
         {"action": "store",
          "dest": "signed_input",
          "type": "string",
+         "default": os.environ.get('SIGNED_INPUT'),
          "help": "Specify the signed input (url)"}
     ], [
         ['--output-file', ],
         {"action": "store",
          "dest": "output_file",
          "type": "string",
          "help": "Specify the output filename"}
     ]]
@@ -33,16 +34,20 @@ class Repackage(BaseScript):
         }
         BaseScript.__init__(
             self,
             config_options=self.config_options,
             require_config_file=require_config_file,
             **script_kwargs
         )
 
+        # Assert we have it either passed in or in environment
+        assert self.config.get('signed_input'), \
+            "Must pass --signed-input or be set in the environment as SIGNED_INPUT"
+
     def download_input(self):
         config = self.config
 
         url = config['signed_input']
         status = self.download_file(url=url,
                                     file_name=config['input_filename'],
                                     parent_dir=config['input_home'])
         if not status: