diff --git a/builder/dockerfile/internals.go b/builder/dockerfile/internals.go
index c9fcb15f54..a5a46e538a 100644
--- a/builder/dockerfile/internals.go
+++ b/builder/dockerfile/internals.go
@@ -172,7 +172,7 @@ func (b *Builder) runContextCommand(args []string, allowRemote bool, allowLocalD
 	}
 
 	cmd := b.runConfig.Cmd
-	b.runConfig.Cmd = strslice.StrSlice(append(getShell(b.runConfig), "#(nop) %s %s in %s ", cmdName, srcHash, dest))
+	b.runConfig.Cmd = strslice.StrSlice(append(getShell(b.runConfig), fmt.Sprintf("#(nop) %s %s in %s ", cmdName, srcHash, dest)))
 	defer func(cmd strslice.StrSlice) { b.runConfig.Cmd = cmd }(cmd)
 
 	if hit, err := b.probeCache(); err != nil {
diff --git a/contrib/check-config.sh b/contrib/check-config.sh
index c71c81930e..8279639090 100755
--- a/contrib/check-config.sh
+++ b/contrib/check-config.sh
@@ -232,6 +232,7 @@ flags=(
 	CGROUP_HUGETLB
 	NET_CLS_CGROUP $netprio
 	CFS_BANDWIDTH FAIR_GROUP_SCHED RT_GROUP_SCHED
+	IP_VS
 )
 check_flags "${flags[@]}"
 
diff --git a/docs/userguide/storagedriver/zfs-driver.md b/docs/userguide/storagedriver/zfs-driver.md
index 0d29f128ab..87d2472240 100644
--- a/docs/userguide/storagedriver/zfs-driver.md
+++ b/docs/userguide/storagedriver/zfs-driver.md
@@ -129,6 +129,27 @@ Stop the Docker daemon. Then, ensure that you have a spare block device at
 `/dev/xvdb`. The device identifier may be be different in your environment and 
 you should substitute your own values throughout the procedure.
 
+### Install Zfs on Ubuntu 16.04 LTS
+
+1. If it is running, stop the Docker `daemon`.
+
+2. Install the `zfs` package.
+
+        $ sudo apt-get install -y zfs
+        Reading package lists... Done
+        Building dependency tree
+        <output truncated>
+
+3. Verify that the `zfs` module is loaded correctly.
+
+        $ lsmod | grep zfs
+        zfs                  2813952  3
+        zunicode              331776  1 zfs
+        zcommon                57344  1 zfs
+        znvpair                90112  2 zfs,zcommon
+        spl                   102400  3 zfs,zcommon,znvpair
+        zavl                   16384  1 zfs
+
 ### Install Zfs on Ubuntu 14.04 LTS
 
 1. If it is running, stop the Docker `daemon`.