diff --git a/libraries/chain/include/graphene/chain/config.hpp b/libraries/chain/include/graphene/chain/config.hpp
index a5354f85..5e4851b9 100644
--- a/libraries/chain/include/graphene/chain/config.hpp
+++ b/libraries/chain/include/graphene/chain/config.hpp
@@ -227,6 +227,9 @@
 #define TOURNAMENT_MAX_WHITELIST_LENGTH                     1000
 #define TOURNAMENT_MAX_START_TIME_IN_FUTURE                 (60*60*24*7*4) // 1 month
 #define TOURNAMENT_MAX_START_DELAY                          (60*60*24*7) // 1 week
+#define GPOS_PERIOD                                         (60*60*24*30*6) // 6 months
+#define GPOS_SUBPERIOD                                      (60*60*24*30) // 1 month
+#define MIN_SON_MEMBER_COUNT                                15
 
 #define SWEEPS_DEFAULT_DISTRIBUTION_PERCENTAGE              (2*GRAPHENE_1_PERCENT)
 #define SWEEPS_DEFAULT_DISTRIBUTION_ASSET                   (graphene::chain::asset_id_type(0))
diff --git a/libraries/chain/include/graphene/chain/protocol/chain_parameters.hpp b/libraries/chain/include/graphene/chain/protocol/chain_parameters.hpp
index 647d3f99..90bf7088 100644
--- a/libraries/chain/include/graphene/chain/protocol/chain_parameters.hpp
+++ b/libraries/chain/include/graphene/chain/protocol/chain_parameters.hpp
@@ -37,6 +37,11 @@ namespace graphene { namespace chain {
       optional< uint16_t >            betting_rake_fee_percentage;
       optional< flat_map<bet_multiplier_type, bet_multiplier_type> > permitted_betting_odds_increments;
       optional< uint16_t >            live_betting_delay_time;
+      /* gpos parameters */
+      optional < uint32_t >           gpos_period;
+      optional < uint32_t >           gpos_subperiod;
+      optional < uint32_t >           gpos_period_start;
+      optional < uint16_t >           son_count;
       optional< uint16_t >            sweeps_distribution_percentage;
       optional< asset_id_type >       sweeps_distribution_asset;
       optional< account_id_type >     sweeps_vesting_accumulator_account;
@@ -119,6 +124,9 @@ namespace graphene { namespace chain {
       inline account_id_type sweeps_vesting_accumulator_account()const {
          return extensions.value.sweeps_vesting_accumulator_account.valid() ? *extensions.value.sweeps_vesting_accumulator_account : SWEEPS_ACCUMULATOR_ACCOUNT;
       }
+      inline uint16_t son_count()const {
+         return extensions.value.son_count.valid() ? *extensions.value.son_count : MIN_SON_MEMBER_COUNT;
+      }
    };
 
 } }  // graphene::chain
@@ -129,6 +137,10 @@ FC_REFLECT( graphene::chain::parameter_extension,
    (betting_rake_fee_percentage)
    (permitted_betting_odds_increments)
    (live_betting_delay_time)
+   (gpos_period)
+   (gpos_subperiod)
+   (gpos_period_start)
+   (son_count)
    (sweeps_distribution_percentage)
    (sweeps_distribution_asset)
    (sweeps_vesting_accumulator_account)
diff --git a/programs/delayed_node/main.cpp b/programs/delayed_node/main.cpp
index 5894dcf8..3e058b64 100644
--- a/programs/delayed_node/main.cpp
+++ b/programs/delayed_node/main.cpp
@@ -169,6 +169,7 @@ int main(int argc, char** argv) {
          elog("Error parsing configuration file: ${e}", ("e", e.what()));
          return 1;
       }
+
       if( !options.count("plugins") )
          options.insert( std::make_pair( "plugins", bpo::variable_value(std::string("delayed_node account_history market_history"), true) ) );
 
diff --git a/programs/witness_node/main.cpp b/programs/witness_node/main.cpp
index 2b3ab13a..6675ee87 100644
--- a/programs/witness_node/main.cpp
+++ b/programs/witness_node/main.cpp
@@ -50,14 +50,14 @@
 #include <iostream>
 
 #ifdef WIN32
-# include <signal.h> 
+# include <signal.h>
 #else
 # include <csignal>
 #endif
 
 using namespace graphene;
 namespace bpo = boost::program_options;
-         
+
 int main(int argc, char** argv) {
    app::application* node = new app::application();
    fc::oexception unhandled_exception;
@@ -193,4 +193,3 @@ int main(int argc, char** argv) {
       return EXIT_FAILURE;
    }
 }
-