diff --git a/db.go b/db.go
index 67c1b46..f5c103d 100644
--- a/db.go
+++ b/db.go
@@ -149,7 +149,7 @@ func (db *DB) mmap() error {
 
 	// Determine the map size based on the file size.
 	var size int
-	if info, err := db.os.Stat(db.path); err != nil {
+	if info, err := db.file.Stat(); err != nil {
 		return err
 	} else if info.Size() < int64(db.pageSize*2) {
 		return &Error{"file size too small", nil}
@@ -188,7 +188,7 @@ func (db *DB) init() error {
 	for i := 0; i < 2; i++ {
 		p := db.page(buf[:], i)
 		p.id = pgno(i)
-		p.initMeta(db.pageSize)
+		p.init(db.pageSize)
 	}
 
 	// Write the buffer to our data file.
diff --git a/db_test.go b/db_test.go
index a6ad919..cf36c37 100644
--- a/db_test.go
+++ b/db_test.go
@@ -1,11 +1,17 @@
 package bolt
 
 import (
+	"errors"
+	"io"
 	"io/ioutil"
 	"os"
+	"syscall"
 	"testing"
+	"time"
+	"unsafe"
 
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/mock"
 )
 
 // Ensure that a database can be opened without error.
@@ -28,9 +34,9 @@ func TestDBReopen(t *testing.T) {
 
 // Ensure that the database returns an error if the file handle cannot be open.
 func TestDBOpenFileError(t *testing.T) {
-	withMockDB(func(db *DB, mockos *mockos, path string) {
+	withMockDB(func(db *DB, mockos *mockos, mocksyscall *mocksyscall, path string) {
 		exp := &os.PathError{}
-		mockos.On("OpenFile", path, os.O_RDWR|os.O_CREATE, os.FileMode(0666)).Return((*os.File)(nil), exp)
+		mockos.On("OpenFile", path, os.O_RDWR|os.O_CREATE, os.FileMode(0666)).Return((*mockfile)(nil), exp)
 		err := db.Open(path, 0666)
 		assert.Equal(t, err, exp)
 	})
@@ -38,28 +44,141 @@ func TestDBOpenFileError(t *testing.T) {
 
 // Ensure that the database returns an error if the meta file handle cannot be open.
 func TestDBOpenMetaFileError(t *testing.T) {
-	withMockDB(func(db *DB, mockos *mockos, path string) {
+	withMockDB(func(db *DB, mockos *mockos, mocksyscall *mocksyscall, path string) {
 		exp := &os.PathError{}
-		mockos.On("OpenFile", path, os.O_RDWR|os.O_CREATE, os.FileMode(0666)).Return(&os.File{}, nil)
-		mockos.On("OpenFile", path, os.O_RDWR|os.O_SYNC, os.FileMode(0666)).Return((*os.File)(nil), exp)
+		mockos.On("OpenFile", path, os.O_RDWR|os.O_CREATE, os.FileMode(0666)).Return(&mockfile{}, nil)
+		mockos.On("OpenFile", path, os.O_RDWR|os.O_SYNC, os.FileMode(0666)).Return((*mockfile)(nil), exp)
 		err := db.Open(path, 0666)
 		assert.Equal(t, err, exp)
 	})
 }
 
 // Ensure that the database limits the upper bound of the page size.
-/*
 func TestDBLimitPageSize(t *testing.T) {
-	withMockDB(func(db *DB, mockos *mockos, path string) {
-		buf := make([]byte, 4096)
-		mockos.On("OpenFile", path, os.O_RDWR|os.O_CREATE, os.FileMode(0666)).Return(&mockfile{}, nil)
-		mockos.On("OpenFile", path, os.O_RDWR|os.O_SYNC, os.FileMode(0666)).Return(&mockfile{}, nil)
-		mockos.On("OpenFile", path, os.O_RDWR|os.O_SYNC, os.FileMode(0666)).Return(&mockfile{}, nil)
+	withMockDB(func(db *DB, mockos *mockos, mocksyscall *mocksyscall, path string) {
+		b := make([]byte, 0x10000)
+		p0, p1 := (*page)(unsafe.Pointer(&b[0x0000])), (*page)(unsafe.Pointer(&b[0x8000]))
+		p0.init(0x8000)
+		p1.init(0x8000)
+		file, metafile := &mockfile{}, &mockfile{}
+		mockos.On("OpenFile", path, os.O_RDWR|os.O_CREATE, os.FileMode(0666)).Return(file, nil)
+		mockos.On("OpenFile", path, os.O_RDWR|os.O_SYNC, os.FileMode(0666)).Return(metafile, nil)
+		mockos.On("Getpagesize").Return(0x10000)
+		file.On("ReadAt", mock.Anything, int64(0)).Return(0, nil)
+		file.On("Stat").Return(&mockfileinfo{"", 0x10000, 0666, time.Now(), false, nil}, nil)
+		metafile.On("WriteAt", mock.Anything, int64(0)).Return(0, nil)
+		mocksyscall.On("Mmap", 0, int64(0), 0x10000, syscall.PROT_READ, syscall.MAP_SHARED).Return(b, nil)
+		db.Open(path, 0666)
+		assert.Equal(t, db.pageSize, maxPageSize)
+	})
+}
+
+// Ensure that write errors to the meta file handler during initialization are returned.
+func TestDBMetaInitWriteError(t *testing.T) {
+	withMockDB(func(db *DB, mockos *mockos, mocksyscall *mocksyscall, path string) {
+		file, metafile := &mockfile{}, &mockfile{}
+		mockos.On("OpenFile", path, os.O_RDWR|os.O_CREATE, os.FileMode(0666)).Return(file, nil)
+		mockos.On("OpenFile", path, os.O_RDWR|os.O_SYNC, os.FileMode(0666)).Return(metafile, nil)
+		mockos.On("Getpagesize").Return(0x10000)
+		file.On("ReadAt", mock.Anything, int64(0)).Return(0, nil)
+		file.On("Stat").Return(&mockfileinfo{"", 0x10000, 0666, time.Now(), false, nil}, nil)
+		metafile.On("WriteAt", mock.Anything, int64(0)).Return(0, io.ErrShortWrite)
+		err := db.Open(path, 0666)
+		assert.Equal(t, err, io.ErrShortWrite)
+	})
+}
+
+// Ensure that a database that is too small returns an error.
+func TestDBFileTooSmall(t *testing.T) {
+	withMockDB(func(db *DB, mockos *mockos, mocksyscall *mocksyscall, path string) {
+		file, metafile := &mockfile{}, &mockfile{}
+		mockos.On("OpenFile", path, os.O_RDWR|os.O_CREATE, os.FileMode(0666)).Return(file, nil)
+		mockos.On("OpenFile", path, os.O_RDWR|os.O_SYNC, os.FileMode(0666)).Return(metafile, nil)
+		mockos.On("Getpagesize").Return(0x1000)
+		file.On("ReadAt", mock.Anything, int64(0)).Return(0, nil)
+		file.On("Stat").Return(&mockfileinfo{"", 0x1000, 0666, time.Now(), false, nil}, nil)
+		metafile.On("WriteAt", mock.Anything, int64(0)).Return(0, nil)
+		err := db.Open(path, 0666)
+		assert.Equal(t, err, &Error{"file size too small", nil})
+	})
+}
+
+// Ensure that stat errors during mmap get returned.
+func TestDBMmapStatError(t *testing.T) {
+	withMockDB(func(db *DB, mockos *mockos, mocksyscall *mocksyscall, path string) {
+		exp := &os.PathError{}
+		file, metafile := &mockfile{}, &mockfile{}
+		mockos.On("OpenFile", path, os.O_RDWR|os.O_CREATE, os.FileMode(0666)).Return(file, nil)
+		mockos.On("OpenFile", path, os.O_RDWR|os.O_SYNC, os.FileMode(0666)).Return(metafile, nil)
+		mockos.On("Getpagesize").Return(0x1000)
+		file.On("ReadAt", mock.Anything, int64(0)).Return(0, nil)
+		file.On("Stat").Return((*mockfileinfo)(nil), exp)
+		metafile.On("WriteAt", mock.Anything, int64(0)).Return(0, nil)
 		err := db.Open(path, 0666)
 		assert.Equal(t, err, exp)
 	})
 }
-*/
+
+// Ensure that mmap errors get returned.
+func TestDBMmapError(t *testing.T) {
+	withMockDB(func(db *DB, mockos *mockos, mocksyscall *mocksyscall, path string) {
+		exp := errors.New("")
+		file, metafile := &mockfile{}, &mockfile{}
+		mockos.On("OpenFile", path, os.O_RDWR|os.O_CREATE, os.FileMode(0666)).Return(file, nil)
+		mockos.On("OpenFile", path, os.O_RDWR|os.O_SYNC, os.FileMode(0666)).Return(metafile, nil)
+		mockos.On("Getpagesize").Return(0x1000)
+		file.On("ReadAt", mock.Anything, int64(0)).Return(0, nil)
+		file.On("Stat").Return(&mockfileinfo{"", 0x2000, 0666, time.Now(), false, nil}, nil)
+		metafile.On("WriteAt", mock.Anything, int64(0)).Return(0, nil)
+		mocksyscall.On("Mmap", 0, int64(0), 0x2000, syscall.PROT_READ, syscall.MAP_SHARED).Return(([]byte)(nil), exp)
+		err := db.Open(path, 0666)
+		assert.Equal(t, err, exp)
+	})
+}
+
+// Ensure that corrupt meta0 page errors get returned.
+func TestDBCorruptMeta0(t *testing.T) {
+	withMockDB(func(db *DB, mockos *mockos, mocksyscall *mocksyscall, path string) {
+		b := make([]byte, 0x10000)
+		p0, p1 := (*page)(unsafe.Pointer(&b[0x0000])), (*page)(unsafe.Pointer(&b[0x8000]))
+		p0.init(0x8000)
+		p1.init(0x8000)
+		m, _ := p0.meta()
+		m.magic = 0
+		file, metafile := &mockfile{}, &mockfile{}
+		mockos.On("OpenFile", path, os.O_RDWR|os.O_CREATE, os.FileMode(0666)).Return(file, nil)
+		mockos.On("OpenFile", path, os.O_RDWR|os.O_SYNC, os.FileMode(0666)).Return(metafile, nil)
+		mockos.On("Getpagesize").Return(0x10000)
+		file.On("ReadAt", mock.Anything, int64(0)).Return(0, nil)
+		file.On("Stat").Return(&mockfileinfo{"", 0x10000, 0666, time.Now(), false, nil}, nil)
+		metafile.On("WriteAt", mock.Anything, int64(0)).Return(0, nil)
+		mocksyscall.On("Mmap", 0, int64(0), 0x10000, syscall.PROT_READ, syscall.MAP_SHARED).Return(b, nil)
+		err := db.Open(path, 0666)
+		assert.Equal(t, err, &Error{"meta0 error", InvalidError})
+	})
+}
+
+// Ensure that corrupt meta1 page errors get returned.
+func TestDBCorruptMeta1(t *testing.T) {
+	withMockDB(func(db *DB, mockos *mockos, mocksyscall *mocksyscall, path string) {
+		b := make([]byte, 0x10000)
+		p0, p1 := (*page)(unsafe.Pointer(&b[0x0000])), (*page)(unsafe.Pointer(&b[0x8000]))
+		p0.init(0x8000)
+		p1.init(0x8000)
+		m, _ := p1.meta()
+		m.version = 100
+		file, metafile := &mockfile{}, &mockfile{}
+		mockos.On("OpenFile", path, os.O_RDWR|os.O_CREATE, os.FileMode(0666)).Return(file, nil)
+		mockos.On("OpenFile", path, os.O_RDWR|os.O_SYNC, os.FileMode(0666)).Return(metafile, nil)
+		mockos.On("Getpagesize").Return(0x10000)
+		file.On("ReadAt", mock.Anything, int64(0)).Return(0, nil)
+		file.On("Stat").Return(&mockfileinfo{"", 0x10000, 0666, time.Now(), false, nil}, nil)
+		metafile.On("WriteAt", mock.Anything, int64(0)).Return(0, nil)
+		mocksyscall.On("Mmap", 0, int64(0), 0x10000, syscall.PROT_READ, syscall.MAP_SHARED).Return(b, nil)
+		err := db.Open(path, 0666)
+		assert.Equal(t, err, &Error{"meta1 error", VersionMismatchError})
+	})
+}
 
 // withDB executes a function with a database reference.
 func withDB(fn func(*DB, string)) {
@@ -74,9 +193,10 @@ func withDB(fn func(*DB, string)) {
 }
 
 // withMockDB executes a function with a database reference and a mock filesystem.
-func withMockDB(fn func(*DB, *mockos, string)) {
-	os := &mockos{}
+func withMockDB(fn func(*DB, *mockos, *mocksyscall, string)) {
+	os, syscall := &mockos{}, &mocksyscall{}
 	db := NewDB()
 	db.os = os
-	fn(db, os, "/mock/db")
+	db.syscall = syscall
+	fn(db, os, syscall, "/mock/db")
 }
diff --git a/file.go b/file.go
index d571124..9395d89 100644
--- a/file.go
+++ b/file.go
@@ -1,7 +1,12 @@
 package bolt
 
+import (
+	"os"
+)
+
 type file interface {
 	Fd() uintptr
 	ReadAt(b []byte, off int64) (n int, err error)
+	Stat() (fi os.FileInfo, err error)
 	WriteAt(b []byte, off int64) (n int, err error)
 }
diff --git a/file_test.go b/file_test.go
index 7f35c22..f001160 100644
--- a/file_test.go
+++ b/file_test.go
@@ -1,6 +1,9 @@
 package bolt
 
 import (
+	"os"
+	"time"
+
 	"github.com/stretchr/testify/mock"
 )
 
@@ -18,7 +21,45 @@ func (m *mockfile) ReadAt(b []byte, off int64) (n int, err error) {
 	return args.Int(0), args.Error(1)
 }
 
+func (m *mockfile) Stat() (os.FileInfo, error) {
+	args := m.Called()
+	return args.Get(0).(os.FileInfo), args.Error(1)
+}
+
 func (m *mockfile) WriteAt(b []byte, off int64) (n int, err error) {
 	args := m.Called(b, off)
 	return args.Int(0), args.Error(1)
 }
+
+type mockfileinfo struct {
+	name    string
+	size    int64
+	mode    os.FileMode
+	modTime time.Time
+	isDir   bool
+	sys     interface{}
+}
+
+func (m *mockfileinfo) Name() string {
+	return m.name
+}
+
+func (m *mockfileinfo) Size() int64 {
+	return m.size
+}
+
+func (m *mockfileinfo) Mode() os.FileMode {
+	return m.mode
+}
+
+func (m *mockfileinfo) ModTime() time.Time {
+	return m.modTime
+}
+
+func (m *mockfileinfo) IsDir() bool {
+	return m.isDir
+}
+
+func (m *mockfileinfo) Sys() interface{} {
+	return m.sys
+}
diff --git a/os.go b/os.go
index ab415a9..f8945bf 100644
--- a/os.go
+++ b/os.go
@@ -5,14 +5,14 @@ import (
 )
 
 type _os interface {
-	OpenFile(name string, flag int, perm os.FileMode) (file *os.File, err error)
+	OpenFile(name string, flag int, perm os.FileMode) (file file, err error)
 	Stat(name string) (fi os.FileInfo, err error)
 	Getpagesize() int
 }
 
 type sysos struct{}
 
-func (o *sysos) OpenFile(name string, flag int, perm os.FileMode) (file *os.File, err error) {
+func (o *sysos) OpenFile(name string, flag int, perm os.FileMode) (file file, err error) {
 	return os.OpenFile(name, flag, perm)
 }
 
diff --git a/os_test.go b/os_test.go
index 17ab09f..8a9808e 100644
--- a/os_test.go
+++ b/os_test.go
@@ -10,9 +10,9 @@ type mockos struct {
 	mock.Mock
 }
 
-func (m *mockos) OpenFile(name string, flag int, perm os.FileMode) (file *os.File, err error) {
+func (m *mockos) OpenFile(name string, flag int, perm os.FileMode) (file file, err error) {
 	args := m.Called(name, flag, perm)
-	return args.Get(0).(*os.File), args.Error(1)
+	return args.Get(0).(*mockfile), args.Error(1)
 }
 
 func (m *mockos) Stat(name string) (fi os.FileInfo, err error) {
diff --git a/page.go b/page.go
index 522f113..5827f96 100644
--- a/page.go
+++ b/page.go
@@ -78,8 +78,8 @@ func (p *page) meta() (*meta, error) {
 	return m, nil
 }
 
-// initMeta initializes a page as a new meta page.
-func (p *page) initMeta(pageSize int) {
+// init initializes a page as a new meta page.
+func (p *page) init(pageSize int) {
 	p.flags = p_meta
 	m := (*meta)(unsafe.Pointer(&p.ptr))
 	m.magic = magic