diff --git a/lib/Dist/Zilla/Tester.pm b/lib/Dist/Zilla/Tester.pm
index 4115cfa78..982aa23c3 100644
--- a/lib/Dist/Zilla/Tester.pm
+++ b/lib/Dist/Zilla/Tester.pm
@@ -276,7 +276,9 @@ sub minter { 'Dist::Zilla::Tester::_Minter' }
 
     my $global_config_root = Path::Class::dir($tester_arg->{global_config_root})->absolute;
 
-    local $ENV{DZIL_GLOBAL_CONFIG_ROOT} = $global_config_root;
+    local $ENV{DZIL_GLOBAL_CONFIG_ROOT};
+    $ENV{DZIL_GLOBAL_CONFIG_ROOT} = $tester_arg->{global_config_root}
+      if defined $ENV{DZIL_GLOBAL_CONFIG_ROOT};
 
     my $global_stashes = $self->_setup_global_config(
       $global_config_root,