--- a/testing/xpcshell/mach_test_package_commands.py
+++ b/testing/xpcshell/mach_test_package_commands.py
@@ -17,17 +17,16 @@ from mach.decorators import (
     CommandProvider,
     Command,
 )
 
 
 def run_xpcshell(context, **kwargs):
     args = Namespace(**kwargs)
     args.appPath = args.appPath or os.path.dirname(context.firefox_bin)
-    args.e10s = context.mozharness_config.get('e10s', args.e10s)
     args.utility_path = context.bin_dir
     args.testingModulesDir = context.modules_dir
 
     if not args.xpcshell:
         args.xpcshell = os.path.join(args.appPath, 'xpcshell')
 
     if not args.pluginsPath:
         for path in context.ancestors(args.appPath, depth=2):