diff --git a/common_windows.go b/common_windows.go
index 5ba012e..2f981d1 100644
--- a/common_windows.go
+++ b/common_windows.go
@@ -9,3 +9,8 @@ import (
 var (
 	modKernel32 = syscall.NewLazyDLL("kernel32.dll")
 )
+
+type FILETIME struct {
+	DwLowDateTime  uint32
+	DwHighDateTime uint32
+}
diff --git a/cpu_windows.go b/cpu_windows.go
index 70134c7..c34a116 100644
--- a/cpu_windows.go
+++ b/cpu_windows.go
@@ -12,11 +12,6 @@ var (
 	procGetSystemTimes = modkernel32.NewProc("GetSystemTimes")
 )
 
-type FILETIME struct {
-	DwLowDateTime  uint32
-	DwHighDateTime uint32
-}
-
 func Cpu_times() ([]CPU_TimesStat, error) {
 	ret := make([]CPU_TimesStat, 0)
 
diff --git a/host_windows.go b/host_windows.go
index 3ed1f78..45e0d29 100644
--- a/host_windows.go
+++ b/host_windows.go
@@ -6,6 +6,12 @@ import (
 	"github.com/mitchellh/go-ps"
 	"os"
 	"syscall"
+	"unsafe"
+)
+
+var (
+	procGetSystemTimeAsFileTime = modKernel32.NewProc("GetSystemTimeAsFileTime")
+	procGetTickCount            = modKernel32.NewProc("GetTickCount")
 )
 
 func HostInfo() (HostInfoStat, error) {
@@ -39,8 +45,24 @@ func HostInfo() (HostInfoStat, error) {
 }
 
 func Boot_time() (int64, error) {
+	var lpSystemTimeAsFileTime FILETIME
 
-	return 0, nil
+	r, _, _ := procGetSystemTimeAsFileTime.Call(uintptr(unsafe.Pointer(&lpSystemTimeAsFileTime)))
+	if r == 0 {
+		return 0, syscall.GetLastError()
+	}
+
+	// TODO: This calc is wrong.
+	ll := (uint32(lpSystemTimeAsFileTime.DwHighDateTime))<<32 + lpSystemTimeAsFileTime.DwLowDateTime
+	pt := (uint64(ll) - 116444736000000000) / 10000000
+
+	u, _, _ := procGetTickCount.Call()
+	if u == 0 {
+		return 0, syscall.GetLastError()
+	}
+	uptime := uint64(u) / 1000
+
+	return int64(pt - uptime), nil
 }
 func Users() ([]UserStat, error) {