diff --git a/libcontainer/cgroups/fs/cpuset.go b/libcontainer/cgroups/fs/cpuset.go
index 101b9b1ed7f..cfc7b211a68 100644
--- a/libcontainer/cgroups/fs/cpuset.go
+++ b/libcontainer/cgroups/fs/cpuset.go
@@ -5,6 +5,7 @@ package fs
 import (
 	"bytes"
 	"errors"
+	"fmt"
 	"io/ioutil"
 	"os"
 	"path/filepath"