diff --git a/pkg/repository/provider_redis.go b/pkg/repository/provider_redis.go
index 9dca4df20..6797fbb5c 100644
--- a/pkg/repository/provider_redis.go
+++ b/pkg/repository/provider_redis.go
@@ -313,6 +313,13 @@ func (r *ProviderRedisRepository) RegisterMachine(providerName, poolName, machin
 		machineInfo.LastKeepalive = fmt.Sprintf("%d", time.Now().UTC().Unix())
 		machineInfo.PoolName = newMachineInfo.PoolName
 		machineInfo.MachineId = newMachineInfo.MachineId
+
+		// Add machine to index
+		machineIndexKey := common.RedisKeys.ProviderMachineIndex(providerName, poolName)
+		err = r.rdb.SAdd(context.TODO(), machineIndexKey, stateKey).Err()
+		if err != nil {
+			return fmt.Errorf("failed to add machine state key to index <%v>: %w", machineIndexKey, err)
+		}
 	}
 
 	machineInfo.HostName = newMachineInfo.HostName
diff --git a/pkg/scheduler/pool_sizing_test.go b/pkg/scheduler/pool_sizing_test.go
index e01303f32..776544898 100644
--- a/pkg/scheduler/pool_sizing_test.go
+++ b/pkg/scheduler/pool_sizing_test.go
@@ -255,6 +255,12 @@ func TestOccupyAvailableMachines(t *testing.T) {
 	})
 	assert.NoError(t, err)
 
+	poolConfig := &types.WorkerPoolConfig{
+		Provider: &types.ProviderLambdaLabs,
+		GPUType:  "A10G",
+		Mode:     types.PoolModeExternal,
+	}
+
 	err = providerRepo.RegisterMachine(string(types.ProviderLambdaLabs), lambdaPoolName, "machine1", &types.ProviderMachineState{
 		Gpu:             "A10G",
 		GpuCount:        1,
@@ -262,7 +268,7 @@ func TestOccupyAvailableMachines(t *testing.T) {
 		Cpu:             30000,
 		Memory:          16000,
 		Status:          types.MachineStatusRegistered,
-	})
+	}, poolConfig)
 	assert.NoError(t, err)
 
 	err = providerRepo.AddMachine(string(types.ProviderLambdaLabs), lambdaPoolName, "machine2", &types.ProviderMachineState{
@@ -282,7 +288,7 @@ func TestOccupyAvailableMachines(t *testing.T) {
 		Cpu:             30000,
 		Memory:          16000,
 		Status:          types.MachineStatusRegistered,
-	})
+	}, poolConfig)
 	assert.NoError(t, err)
 	assert.NoError(t, err)
 
@@ -392,6 +398,12 @@ func TestOccupyAvailableMachinesConcurrency(t *testing.T) {
 		},
 	}
 
+	poolConfig := &types.WorkerPoolConfig{
+		Provider: &types.ProviderGeneric,
+		GPUType:  "A10G",
+		Mode:     types.PoolModeExternal,
+	}
+
 	maxMachinesAndWorkers := 100
 	for i := 0; i < maxMachinesAndWorkers; i++ {
 		machineName := fmt.Sprintf("machine-%d", i)
@@ -406,7 +418,7 @@ func TestOccupyAvailableMachinesConcurrency(t *testing.T) {
 		err = providerRepo.AddMachine(string(types.ProviderGeneric), poolName, machineName, machineState)
 		assert.NoError(t, err)
 
-		err = providerRepo.RegisterMachine(string(types.ProviderGeneric), poolName, machineName, machineState)
+		err = providerRepo.RegisterMachine(string(types.ProviderGeneric), poolName, machineName, machineState, poolConfig)
 		assert.NoError(t, err)
 	}