diff --git a/pkg/scheduler/firstfit.go b/pkg/scheduler/firstfit.go
index e1e088c5cc4..250fa99faf1 100644
--- a/pkg/scheduler/firstfit.go
+++ b/pkg/scheduler/firstfit.go
@@ -19,16 +19,17 @@ package scheduler
 import (
 	"fmt"
 	"math/rand"
+	"sync"
 
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/api"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/labels"
 )
 
-// FirstFitScheduler is a Scheduler interface implementation which uses first fit algorithm.
+// FirstFitScheduler is a Scheduler which schedules a Pod on a random machine which matches its requirement.
 type FirstFitScheduler struct {
-	podLister PodLister
-	// TODO: *rand.Rand is *not* threadsafe
-	random *rand.Rand
+	podLister  PodLister
+	random     *rand.Rand
+	randomLock sync.Mutex
 }
 
 func MakeFirstFitScheduler(podLister PodLister, random *rand.Rand) Scheduler {
@@ -49,7 +50,7 @@ func (s *FirstFitScheduler) containsPort(pod api.Pod, port api.Port) bool {
 	return false
 }
 
-// Schedule schedules a pod on the first machine which matches its requirement.
+// Schedule schedules a pod on a random machine which matches its requirement.
 func (s *FirstFitScheduler) Schedule(pod api.Pod, minionLister MinionLister) (string, error) {
 	machines, err := minionLister.List()
 	if err != nil {
@@ -83,5 +84,7 @@ func (s *FirstFitScheduler) Schedule(pod api.Pod, minionLister MinionLister) (st
 	if len(machineOptions) == 0 {
 		return "", fmt.Errorf("failed to find fit for %#v", pod)
 	}
+	s.randomLock.Lock()
+	defer s.randomLock.Unlock()
 	return machineOptions[s.random.Int()%len(machineOptions)], nil
 }