diff --git a/libraries/app/include/graphene/app/database_api.hpp b/libraries/app/include/graphene/app/database_api.hpp
index 6f90938d..0faaea0b 100644
--- a/libraries/app/include/graphene/app/database_api.hpp
+++ b/libraries/app/include/graphene/app/database_api.hpp
@@ -192,6 +192,12 @@ class database_api
        */
       optional<signed_transaction> get_recent_transaction_by_id( const transaction_id_type& id )const;
 
+      /**
+       * TODO
+       * 
+       */ 
+      void check_transaction_for_duplicated_operations(const signed_transaction& trx);
+      
       /////////////
       // Globals //
       /////////////
diff --git a/libraries/chain/proposal_evaluator.cpp b/libraries/chain/proposal_evaluator.cpp
index 7a57603a..9d55eaf6 100644
--- a/libraries/chain/proposal_evaluator.cpp
+++ b/libraries/chain/proposal_evaluator.cpp
@@ -47,6 +47,7 @@ struct proposal_operation_hardfork_visitor
 
    void operator()(const committee_member_update_global_parameters_operation &op) const {
       if( block_time < HARDFORK_1000_TIME ) { // TODO: remove after hf
+         FC_ASSERT( !op.new_parameters.extensions.value.min_bet_multiplier.valid()
                && !op.new_parameters.extensions.value.max_bet_multiplier.valid()
                && !op.new_parameters.extensions.value.betting_rake_fee_percentage.valid()
                && !op.new_parameters.extensions.value.permitted_betting_odds_increments.valid()