diff --git a/bucket.go b/bucket.go
index 0c5bf27..176fa99 100644
--- a/bucket.go
+++ b/bucket.go
@@ -14,13 +14,6 @@ const (
 	MaxValueSize = (1 << 31) - 2
 )
 
-const (
-	maxUint = ^uint(0)
-	minUint = 0
-	maxInt  = int(^uint(0) >> 1)
-	minInt  = -maxInt - 1
-)
-
 const bucketHeaderSize = int(unsafe.Sizeof(bucket{}))
 
 const (
diff --git a/cmd/bolt/main.go b/cmd/bolt/main.go
index 682ba08..e9a7770 100644
--- a/cmd/bolt/main.go
+++ b/cmd/bolt/main.go
@@ -48,12 +48,6 @@ var (
 
 	// ErrPageIDRequired is returned when a required page id is not specified.
 	ErrPageIDRequired = errors.New("page id required")
-
-	// ErrPageNotFound is returned when specifying a page above the high water mark.
-	ErrPageNotFound = errors.New("page not found")
-
-	// ErrPageFreed is returned when reading a page that has already been freed.
-	ErrPageFreed = errors.New("page freed")
 )
 
 // PageHeaderSize represents the size of the bolt.page header.
@@ -1023,12 +1017,12 @@ func (cmd *BenchCommand) runWritesRandom(db *bolt.DB, options *BenchOptions, res
 
 func (cmd *BenchCommand) runWritesSequentialNested(db *bolt.DB, options *BenchOptions, results *BenchResults) error {
 	var i = uint32(0)
-	return cmd.runWritesWithSource(db, options, results, func() uint32 { i++; return i })
+	return cmd.runWritesNestedWithSource(db, options, results, func() uint32 { i++; return i })
 }
 
 func (cmd *BenchCommand) runWritesRandomNested(db *bolt.DB, options *BenchOptions, results *BenchResults) error {
 	r := rand.New(rand.NewSource(time.Now().UnixNano()))
-	return cmd.runWritesWithSource(db, options, results, func() uint32 { return r.Uint32() })
+	return cmd.runWritesNestedWithSource(db, options, results, func() uint32 { return r.Uint32() })
 }
 
 func (cmd *BenchCommand) runWritesWithSource(db *bolt.DB, options *BenchOptions, results *BenchResults, keySource func() uint32) error {
diff --git a/db.go b/db.go
index c9d800f..db3843c 100644
--- a/db.go
+++ b/db.go
@@ -7,9 +7,7 @@ import (
 	"log"
 	"os"
 	"runtime"
-	"runtime/debug"
 	"sort"
-	"strings"
 	"sync"
 	"time"
 	"unsafe"
@@ -193,6 +191,7 @@ func Open(path string, mode os.FileMode, options *Options) (*DB, error) {
 	// The database file is locked using the shared lock (more than one process may
 	// hold a lock at the same time) otherwise (options.ReadOnly is set).
 	if err := flock(db, mode, !db.readOnly, options.Timeout); err != nil {
+		db.lockfile = nil // make 'unused' happy. TODO: rework locks
 		_ = db.close()
 		return nil, err
 	}
@@ -1040,10 +1039,6 @@ func (s *Stats) Sub(other *Stats) Stats {
 	return diff
 }
 
-func (s *Stats) add(other *Stats) {
-	s.TxStats.add(&other.TxStats)
-}
-
 type Info struct {
 	Data     uintptr
 	PageSize int
@@ -1110,11 +1105,3 @@ func _assert(condition bool, msg string, v ...interface{}) {
 		panic(fmt.Sprintf("assertion failed: "+msg, v...))
 	}
 }
-
-func warn(v ...interface{})              { fmt.Fprintln(os.Stderr, v...) }
-func warnf(msg string, v ...interface{}) { fmt.Fprintf(os.Stderr, msg+"\n", v...) }
-
-func printstack() {
-	stack := strings.Join(strings.Split(string(debug.Stack()), "\n")[2:], "\n")
-	fmt.Fprintln(os.Stderr, stack)
-}
diff --git a/db_test.go b/db_test.go
index 46db4d2..dd09a4d 100644
--- a/db_test.go
+++ b/db_test.go
@@ -12,8 +12,6 @@ import (
 	"os"
 	"path/filepath"
 	"regexp"
-	"sort"
-	"strings"
 	"sync"
 	"testing"
 	"time"
@@ -24,12 +22,6 @@ import (
 
 var statsFlag = flag.Bool("stats", false, "show performance stats")
 
-// version is the data file format version.
-const version = 2
-
-// magic is the marker value to indicate that a file is a Bolt DB.
-const magic uint32 = 0xED0CDAED
-
 // pageSize is the size of one page in the data file.
 const pageSize = 4096
 
@@ -1575,40 +1567,6 @@ func tempfile() string {
 	return f.Name()
 }
 
-// mustContainKeys checks that a bucket contains a given set of keys.
-func mustContainKeys(b *bolt.Bucket, m map[string]string) {
-	found := make(map[string]string)
-	if err := b.ForEach(func(k, _ []byte) error {
-		found[string(k)] = ""
-		return nil
-	}); err != nil {
-		panic(err)
-	}
-
-	// Check for keys found in bucket that shouldn't be there.
-	var keys []string
-	for k := range found {
-		if _, ok := m[string(k)]; !ok {
-			keys = append(keys, k)
-		}
-	}
-	if len(keys) > 0 {
-		sort.Strings(keys)
-		panic(fmt.Sprintf("keys found(%d): %s", len(keys), strings.Join(keys, ",")))
-	}
-
-	// Check for keys not found in bucket that should be there.
-	for k := range m {
-		if _, ok := found[string(k)]; !ok {
-			keys = append(keys, k)
-		}
-	}
-	if len(keys) > 0 {
-		sort.Strings(keys)
-		panic(fmt.Sprintf("keys not found(%d): %s", len(keys), strings.Join(keys, ",")))
-	}
-}
-
 func trunc(b []byte, length int) []byte {
 	if length < len(b) {
 		return b[:length]
@@ -1628,15 +1586,9 @@ func fileSize(path string) int64 {
 	return fi.Size()
 }
 
-func warn(v ...interface{})              { fmt.Fprintln(os.Stderr, v...) }
-func warnf(msg string, v ...interface{}) { fmt.Fprintf(os.Stderr, msg+"\n", v...) }
-
 // u64tob converts a uint64 into an 8-byte slice.
 func u64tob(v uint64) []byte {
 	b := make([]byte, 8)
 	binary.BigEndian.PutUint64(b, v)
 	return b
 }
-
-// btou64 converts an 8-byte slice into an uint64.
-func btou64(b []byte) uint64 { return binary.BigEndian.Uint64(b) }