diff --git a/section1/role.harvester.js b/section1/role.harvester.js
index 8cb4b8a..79dc6ea 100644
--- a/section1/role.harvester.js
+++ b/section1/role.harvester.js
@@ -2,7 +2,7 @@ var roleHarvester = {
 
     /** @param {Creep} creep **/
     run: function(creep) {
-        if(creep.carry.energy < creep.carryCapacity) {
+        if(creep.store.getFreeCapacity() > 0) {
             var sources = creep.room.find(FIND_SOURCES);
             if(creep.harvest(sources[0]) == ERR_NOT_IN_RANGE) {
                 creep.moveTo(sources[0]);
diff --git a/section2/role.harvester.js b/section2/role.harvester.js
index bf5d4b7..2d2a5a5 100644
--- a/section2/role.harvester.js
+++ b/section2/role.harvester.js
@@ -2,7 +2,7 @@ var roleHarvester = {
 
     /** @param {Creep} creep **/
     run: function(creep) {
-        if(creep.carry.energy < creep.carryCapacity) {
+        if(creep.store.getFreeCapacity() > 0) {
             var sources = creep.room.find(FIND_SOURCES);
             if(creep.harvest(sources[0]) == ERR_NOT_IN_RANGE) {
                 creep.moveTo(sources[0]);
diff --git a/section2/role.upgrader.js b/section2/role.upgrader.js
index 5c3ba14..9b406b2 100644
--- a/section2/role.upgrader.js
+++ b/section2/role.upgrader.js
@@ -2,7 +2,7 @@ var roleUpgrader = {
 
     /** @param {Creep} creep **/
     run: function(creep) {
-        if(creep.carry.energy == 0) {
+        if(creep.store[RESOURCE_ENERGY] == 0) {
             var sources = creep.room.find(FIND_SOURCES);
             if(creep.harvest(sources[0]) == ERR_NOT_IN_RANGE) {
                 creep.moveTo(sources[0]);
diff --git a/section3/role.builder.js b/section3/role.builder.js
index b97c341..1cbd361 100644
--- a/section3/role.builder.js
+++ b/section3/role.builder.js
@@ -3,11 +3,11 @@ var roleBuilder = {
     /** @param {Creep} creep **/
     run: function(creep) {
 
-        if(creep.memory.building && creep.carry.energy == 0) {
+        if(creep.memory.building && creep.store[RESOURCE_ENERGY] == 0) {
             creep.memory.building = false;
             creep.say('🔄 harvest');
         }
-        if(!creep.memory.building && creep.carry.energy == creep.carryCapacity) {
+        if(!creep.memory.building && creep.store.getFreeCapacity() == 0) {
             creep.memory.building = true;
             creep.say('🚧 build');
         }
diff --git a/section3/role.harvester.js b/section3/role.harvester.js
index d14dd56..8e8618e 100644
--- a/section3/role.harvester.js
+++ b/section3/role.harvester.js
@@ -2,7 +2,7 @@ var roleHarvester = {
 
     /** @param {Creep} creep **/
     run: function(creep) {
-        if(creep.carry.energy < creep.carryCapacity) {
+        if(creep.store.getFreeCapacity() > 0) {
             var sources = creep.room.find(FIND_SOURCES);
             if(creep.harvest(sources[0]) == ERR_NOT_IN_RANGE) {
                 creep.moveTo(sources[0], {visualizePathStyle: {stroke: '#ffaa00'}});
@@ -12,7 +12,7 @@ var roleHarvester = {
             var targets = creep.room.find(FIND_STRUCTURES, {
                 filter: (structure) => {
                     return (structure.structureType == STRUCTURE_EXTENSION || structure.structureType == STRUCTURE_SPAWN) &&
-                        structure.energy < structure.energyCapacity;
+                        structure.store.getFreeCapacity(RESOURCE_ENERGY) > 0;
                 }
             });
             if(targets.length > 0) {
diff --git a/section4/main.js b/section4/main.js
index b3bf661..1b2ac21 100644
--- a/section4/main.js
+++ b/section4/main.js
@@ -14,8 +14,10 @@ module.exports.loop = function () {
     console.log('Harvesters: ' + harvesters.length);
 
     if(harvesters.length < 2) {
-        var newName = Game.spawns['Spawn1'].createCreep([WORK,CARRY,MOVE], undefined, {role: 'harvester'});
+        var newName = 'Harvester' + Game.time;
         console.log('Spawning new harvester: ' + newName);
+        Game.spawns['Spawn1'].spawnCreep([WORK,CARRY,MOVE], newName,
+            {memory: {role: 'harvester'}});
     }
 
     if(Game.spawns['Spawn1'].spawning) {
diff --git a/section4/role.harvester.js b/section4/role.harvester.js
index d14dd56..8e8618e 100644
--- a/section4/role.harvester.js
+++ b/section4/role.harvester.js
@@ -2,7 +2,7 @@ var roleHarvester = {
 
     /** @param {Creep} creep **/
     run: function(creep) {
-        if(creep.carry.energy < creep.carryCapacity) {
+        if(creep.store.getFreeCapacity() > 0) {
             var sources = creep.room.find(FIND_SOURCES);
             if(creep.harvest(sources[0]) == ERR_NOT_IN_RANGE) {
                 creep.moveTo(sources[0], {visualizePathStyle: {stroke: '#ffaa00'}});
@@ -12,7 +12,7 @@ var roleHarvester = {
             var targets = creep.room.find(FIND_STRUCTURES, {
                 filter: (structure) => {
                     return (structure.structureType == STRUCTURE_EXTENSION || structure.structureType == STRUCTURE_SPAWN) &&
-                        structure.energy < structure.energyCapacity;
+                        structure.store.getFreeCapacity(RESOURCE_ENERGY) > 0;
                 }
             });
             if(targets.length > 0) {
diff --git a/section4/role.upgrader.js b/section4/role.upgrader.js
index 8003c0e..f95aafa 100644
--- a/section4/role.upgrader.js
+++ b/section4/role.upgrader.js
@@ -3,11 +3,11 @@ var roleUpgrader = {
     /** @param {Creep} creep **/
     run: function(creep) {
 
-        if(creep.memory.upgrading && creep.carry.energy == 0) {
+        if(creep.memory.upgrading && creep.store[RESOURCE_ENERGY] == 0) {
             creep.memory.upgrading = false;
             creep.say('🔄 harvest');
         }
-        if(!creep.memory.upgrading && creep.carry.energy == creep.carryCapacity) {
+        if(!creep.memory.upgrading && creep.store.getFreeCapacity() == 0) {
             creep.memory.upgrading = true;
             creep.say('⚡ upgrade');
         }
diff --git a/section5/role.builder.js b/section5/role.builder.js
index b97c341..1cbd361 100644
--- a/section5/role.builder.js
+++ b/section5/role.builder.js
@@ -3,11 +3,11 @@ var roleBuilder = {
     /** @param {Creep} creep **/
     run: function(creep) {
 
-        if(creep.memory.building && creep.carry.energy == 0) {
+        if(creep.memory.building && creep.store[RESOURCE_ENERGY] == 0) {
             creep.memory.building = false;
             creep.say('🔄 harvest');
         }
-        if(!creep.memory.building && creep.carry.energy == creep.carryCapacity) {
+        if(!creep.memory.building && creep.store.getFreeCapacity() == 0) {
             creep.memory.building = true;
             creep.say('🚧 build');
         }
diff --git a/section5/role.harvester.js b/section5/role.harvester.js
index e6d1bc3..8963f0d 100644
--- a/section5/role.harvester.js
+++ b/section5/role.harvester.js
@@ -2,7 +2,7 @@ var roleHarvester = {
 
     /** @param {Creep} creep **/
     run: function(creep) {
-        if(creep.carry.energy < creep.carryCapacity) {
+        if(creep.store.getFreeCapacity() > 0) {
             var sources = creep.room.find(FIND_SOURCES);
             if(creep.harvest(sources[0]) == ERR_NOT_IN_RANGE) {
                 creep.moveTo(sources[0], {visualizePathStyle: {stroke: '#ffaa00'}});
@@ -13,7 +13,8 @@ var roleHarvester = {
                 filter: (structure) => {
                     return (structure.structureType == STRUCTURE_EXTENSION ||
                         structure.structureType == STRUCTURE_SPAWN ||
-                        structure.structureType == STRUCTURE_TOWER) && structure.energy < structure.energyCapacity;
+                        structure.structureType == STRUCTURE_TOWER) &&
+                        structure.store.getFreeCapacity(RESOURCE_ENERGY) > 0;
                 }
             });
             if(targets.length > 0) {
diff --git a/section5/role.upgrader.js b/section5/role.upgrader.js
index 8003c0e..f95aafa 100644
--- a/section5/role.upgrader.js
+++ b/section5/role.upgrader.js
@@ -3,11 +3,11 @@ var roleUpgrader = {
     /** @param {Creep} creep **/
     run: function(creep) {
 
-        if(creep.memory.upgrading && creep.carry.energy == 0) {
+        if(creep.memory.upgrading && creep.store[RESOURCE_ENERGY] == 0) {
             creep.memory.upgrading = false;
             creep.say('🔄 harvest');
         }
-        if(!creep.memory.upgrading && creep.carry.energy == creep.carryCapacity) {
+        if(!creep.memory.upgrading && creep.store.getFreeCapacity() == 0) {
             creep.memory.upgrading = true;
             creep.say('⚡ upgrade');
         }