diff --git a/constraints.pro b/constraints.pro
index a27c6b2ea81..1cf0ed5a083 100644
--- a/constraints.pro
+++ b/constraints.pro
@@ -210,13 +210,14 @@ gen_enforced_field(WorkspaceCwd, 'repository.url', RepoUrl) :-
 % The license for all published packages must be MIT unless otherwise specified.
 gen_enforced_field(WorkspaceCwd, 'license', 'MIT') :-
   \+ workspace_field(WorkspaceCwd, 'private', true),
-  WorkspaceCwd \= 'packages/json-rpc-engine',
   WorkspaceCwd \= 'packages/eth-json-rpc-provider'.
 % The following published packages use an ISC license instead of MIT.
 gen_enforced_field(WorkspaceCwd, 'license', 'ISC') :-
   \+ workspace_field(WorkspaceCwd, 'private', true),
-  WorkspaceCwd == 'packages/json-rpc-engine',
   WorkspaceCwd == 'packages/eth-json-rpc-provider'.
+% Non-published packages do not have a license.
+gen_enforced_field(WorkspaceCwd, 'license', null) :-
+  workspace_field(WorkspaceCwd, 'private', true).
 
 % The entrypoint for all published packages must be the same.
 gen_enforced_field(WorkspaceCwd, 'main', './dist/index.js') :-