diff --git a/fs/Android.bp b/fs/Android.bp
index 68cb88d1e..f4706ca2a 100644
--- a/fs/Android.bp
+++ b/fs/Android.bp
@@ -22,6 +22,15 @@ bootstrap_go_package {
     srcs: [
         "fs.go",
     ],
+    darwin: {
+        srcs: [
+            "fs_darwin.go",
+        ],
+    },
+    linux: {
+        srcs: [
+            "fs_linux.go",
+        ],
+    },
 }
 
-
diff --git a/fs/fs.go b/fs/fs.go
index c6060c008..d8ef5315b 100644
--- a/fs/fs.go
+++ b/fs/fs.go
@@ -1,4 +1,4 @@
-// Copyright 2016 Google Inc. All rights reserved.
+// Copyright 2017 Google Inc. All rights reserved.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
@@ -24,7 +24,6 @@ import (
 	"os/user"
 	"path/filepath"
 	"sync"
-	"syscall"
 	"time"
 )
 
@@ -77,33 +76,6 @@ func (osFs) Lstat(path string) (stats os.FileInfo, err error) {
 	return os.Lstat(path)
 }
 
-func (osFs) InodeNumber(info os.FileInfo) (number uint64, err error) {
-	sys := info.Sys()
-	linuxStats, ok := sys.(*syscall.Stat_t)
-	if ok {
-		return linuxStats.Ino, nil
-	}
-	return 0, fmt.Errorf("%v is not a *syscall.Stat_t", sys)
-}
-
-func (osFs) DeviceNumber(info os.FileInfo) (number uint64, err error) {
-	sys := info.Sys()
-	linuxStats, ok := sys.(*syscall.Stat_t)
-	if ok {
-		return linuxStats.Dev, nil
-	}
-	return 0, fmt.Errorf("%v is not a *syscall.Stat_t", sys)
-}
-
-func (osFs) PermTime(info os.FileInfo) (when time.Time, err error) {
-	sys := info.Sys()
-	linuxStats, ok := sys.(*syscall.Stat_t)
-	if ok {
-		return time.Unix(linuxStats.Ctim.Sec, linuxStats.Ctim.Nsec), nil
-	}
-	return time.Date(0, 0, 0, 0, 0, 0, 0, nil), fmt.Errorf("%v is not a *syscall.Stat_t", sys)
-}
-
 func (osFs) ReadDir(path string) (contents []os.FileInfo, err error) {
 	return ioutil.ReadDir(path)
 }
diff --git a/fs/fs_darwin.go b/fs/fs_darwin.go
new file mode 100644
index 000000000..c04883584
--- /dev/null
+++ b/fs/fs_darwin.go
@@ -0,0 +1,49 @@
+// Copyright 2017 Google Inc. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package fs
+
+import (
+	"fmt"
+	"os"
+	"syscall"
+	"time"
+)
+
+func (osFs) InodeNumber(info os.FileInfo) (number uint64, err error) {
+	sys := info.Sys()
+	darwinStats, ok := sys.(*syscall.Stat_t)
+	if ok {
+		return darwinStats.Ino, nil
+	}
+	return 0, fmt.Errorf("%v is not a *syscall.Stat_t", sys)
+}
+
+func (osFs) DeviceNumber(info os.FileInfo) (number uint64, err error) {
+	sys := info.Sys()
+	darwinStats, ok := sys.(*syscall.Stat_t)
+	if ok {
+		return uint64(darwinStats.Dev), nil
+	}
+	return 0, fmt.Errorf("%v is not a *syscall.Stat_t", sys)
+}
+
+func (osFs) PermTime(info os.FileInfo) (when time.Time, err error) {
+	sys := info.Sys()
+	darwinStats, ok := sys.(*syscall.Stat_t)
+	if ok {
+		return time.Unix(darwinStats.Ctimespec.Sec, darwinStats.Ctimespec.Nsec), nil
+	}
+	return time.Time{}, fmt.Errorf("%v is not a *syscall.Stat_t", sys)
+}
diff --git a/fs/fs_linux.go b/fs/fs_linux.go
new file mode 100644
index 000000000..0a22a2c95
--- /dev/null
+++ b/fs/fs_linux.go
@@ -0,0 +1,49 @@
+// Copyright 2017 Google Inc. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package fs
+
+import (
+	"fmt"
+	"os"
+	"syscall"
+	"time"
+)
+
+func (osFs) InodeNumber(info os.FileInfo) (number uint64, err error) {
+	sys := info.Sys()
+	linuxStats, ok := sys.(*syscall.Stat_t)
+	if ok {
+		return linuxStats.Ino, nil
+	}
+	return 0, fmt.Errorf("%v is not a *syscall.Stat_t", sys)
+}
+
+func (osFs) DeviceNumber(info os.FileInfo) (number uint64, err error) {
+	sys := info.Sys()
+	linuxStats, ok := sys.(*syscall.Stat_t)
+	if ok {
+		return linuxStats.Dev, nil
+	}
+	return 0, fmt.Errorf("%v is not a *syscall.Stat_t", sys)
+}
+
+func (osFs) PermTime(info os.FileInfo) (when time.Time, err error) {
+	sys := info.Sys()
+	linuxStats, ok := sys.(*syscall.Stat_t)
+	if ok {
+		return time.Unix(linuxStats.Ctim.Sec, linuxStats.Ctim.Nsec), nil
+	}
+	return time.Time{}, fmt.Errorf("%v is not a *syscall.Stat_t", sys)
+}