diff --git a/agent.go b/agent.go
index ec01250695..a529a17770 100644
--- a/agent.go
+++ b/agent.go
@@ -58,6 +58,8 @@ var initRootfsMounts = []initMount{
 }
 
 type process struct {
+	sync.RWMutex
+
 	id          string
 	process     libcontainer.Process
 	stdin       *os.File
@@ -66,6 +68,7 @@ type process struct {
 	consoleSock *os.File
 	termMaster  *os.File
 	exitCodeCh  chan int
+	stdinClosed bool
 }
 
 type container struct {
diff --git a/grpc.go b/grpc.go
index 37f9f2d96c..4937054525 100644
--- a/grpc.go
+++ b/grpc.go
@@ -1044,6 +1044,16 @@ func (a *agentGRPC) WriteStdin(ctx context.Context, req *pb.WriteStreamRequest)
 		return &pb.WriteStreamResponse{}, err
 	}
 
+	proc.RLock()
+	defer proc.RUnlock()
+	stdinClosed := proc.stdinClosed
+
+	// Ignore this call to WriteStdin() if STDIN has already been closed
+	// earlier.
+	if stdinClosed {
+		return &pb.WriteStreamResponse{}, nil
+	}
+
 	var file *os.File
 	if proc.termMaster != nil {
 		file = proc.termMaster
@@ -1095,10 +1105,15 @@ func (a *agentGRPC) CloseStdin(ctx context.Context, req *pb.CloseStdinRequest) (
 		return emptyResp, nil
 	}
 
+	proc.Lock()
+	defer proc.Unlock()
+
 	if err := proc.stdin.Close(); err != nil {
 		return emptyResp, err
 	}
 
+	proc.stdinClosed = true
+
 	return emptyResp, nil
 }