diff --git a/src/builder.ts b/src/builder.ts
index a8aa13d..dc3a681 100644
--- a/src/builder.ts
+++ b/src/builder.ts
@@ -1,13 +1,10 @@
+import { randomIntInRange } from './utils/Random';
+
 interface BuilderMemory extends CreepMemory {
   building: boolean | undefined;
   sourceNum: number | undefined;
 }
 
-function randomIntInRange(min: number, max: number): number {
-  const delta = max - min;
-  return Math.floor(Math.random() * delta) + min;
-}
-
 export function runAsBuilder(creep: Creep) {
   const memory = creep.memory as BuilderMemory;
 
diff --git a/src/main.ts b/src/main.ts
index 9beede6..243be50 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -16,6 +16,7 @@ enum CreepRole {
 
 function makeCreep(role: CreepRole, count: number) {
   const creeps = Object.values(Game.creeps).filter((c) => c.memory.role === role);
+  console.log('Make creep ', role, 'need', count, 'has', creeps.length);
   if (creeps.length < count) {
     const firstSpawn = _.first(Object.values(Game.spawns));
     const name = makeName(role);
diff --git a/src/upgrader.ts b/src/upgrader.ts
index ce93549..20485bb 100644
--- a/src/upgrader.ts
+++ b/src/upgrader.ts
@@ -1,24 +1,37 @@
+import { randomIntInRange } from './utils/Random';
+
+interface UpgraderMemory extends CreepMemory {
+  upgrading: boolean | undefined;
+  sourceNum: number | undefined;
+}
+
 export function runAsUpgrader(creep: Creep) {
-  const memory = creep.memory as CreepMemory & { upgrading: boolean | undefined };
+  const memory = creep.memory as UpgraderMemory;
 
   if (memory.upgrading && creep.store[RESOURCE_ENERGY] === 0) {
     memory.upgrading = false;
-    creep.say('🔄 harvest');
   }
 
   if (!memory.upgrading && creep.store.getFreeCapacity() === 0) {
     memory.upgrading = true;
-    creep.say('⚡ upgrade');
+  }
+
+  if (memory.sourceNum === undefined) {
+    const sources = creep.room.find(FIND_SOURCES);
+    memory.sourceNum = randomIntInRange(0, sources.length);
   }
 
   if (memory.upgrading) {
     if (creep.room.controller && creep.upgradeController(creep.room.controller) == ERR_NOT_IN_RANGE) {
+      creep.say('⚡ upgrade');
       creep.moveTo(creep.room.controller, { visualizePathStyle: { stroke: '#ffffff' } });
     }
   } else {
     const sources = creep.room.find(FIND_SOURCES);
-    if (creep.harvest(sources[0]) == ERR_NOT_IN_RANGE) {
-      creep.moveTo(sources[0], { visualizePathStyle: { stroke: '#ffaa00' } });
+    const sourceNum = memory.sourceNum;
+    if (creep.harvest(sources[sourceNum]) == ERR_NOT_IN_RANGE) {
+      creep.say('🔄 harvest ' + sourceNum);
+      creep.moveTo(sources[sourceNum], { visualizePathStyle: { stroke: '#ffaa00' } });
     }
   }
 }
diff --git a/src/utils/Random.ts b/src/utils/Random.ts
new file mode 100644
index 0000000..9a4ddca
--- /dev/null
+++ b/src/utils/Random.ts
@@ -0,0 +1,4 @@
+export function randomIntInRange(min: number, max: number): number {
+  const delta = max - min;
+  return Math.floor(Math.random() * delta) + min;
+}