diff --git a/bitcask.go b/bitcask.go
index fab6bdf..5aa2df4 100644
--- a/bitcask.go
+++ b/bitcask.go
@@ -13,7 +13,9 @@ import (
 )
 
 var (
-	ErrKeyNotFound       = errors.New("error: key not found")
+	ErrKeyNotFound    = errors.New("error: key not found")
+	ErrKeyTooLarge    = errors.New("error: key too large")
+	ErrValueTooLarge  = errors.New("error: value too large")
 	ErrDatabaseLocked = errors.New("error: database locked")
 )
 
@@ -67,6 +69,13 @@ func (b *Bitcask) Get(key string) ([]byte, error) {
 }
 
 func (b *Bitcask) Put(key string, value []byte) error {
+	if len(key) > b.opts.MaxKeySize {
+		return ErrKeyTooLarge
+	}
+	if len(value) > b.opts.MaxValueSize {
+		return ErrValueTooLarge
+	}
+
 	index, err := b.put(key, value)
 	if err != nil {
 		return err
diff --git a/bitcask_test.go b/bitcask_test.go
index 0f4ecc1..350927d 100644
--- a/bitcask_test.go
+++ b/bitcask_test.go
@@ -128,6 +128,54 @@ func TestDeletedKeys(t *testing.T) {
 	})
 }
 
+func TestMaxKeySize(t *testing.T) {
+	assert := assert.New(t)
+
+	testdir, err := ioutil.TempDir("", "bitcask")
+	assert.NoError(err)
+
+	var db *Bitcask
+
+	size := 16
+
+	t.Run("Open", func(t *testing.T) {
+		db, err = Open(testdir, WithMaxKeySize(size))
+		assert.NoError(err)
+	})
+
+	t.Run("Put", func(t *testing.T) {
+		key := strings.Repeat(" ", size+1)
+		value := []byte("foobar")
+		err = db.Put(key, value)
+		assert.Error(err)
+		assert.Equal("error: key too large", err.Error())
+	})
+}
+
+func TestMaxValueSize(t *testing.T) {
+	assert := assert.New(t)
+
+	testdir, err := ioutil.TempDir("", "bitcask")
+	assert.NoError(err)
+
+	var db *Bitcask
+
+	size := 16
+
+	t.Run("Open", func(t *testing.T) {
+		db, err = Open(testdir, WithMaxValueSize(size))
+		assert.NoError(err)
+	})
+
+	t.Run("Put", func(t *testing.T) {
+		key := "foo"
+		value := []byte(strings.Repeat(" ", size+1))
+		err = db.Put(key, value)
+		assert.Error(err)
+		assert.Equal("error: value too large", err.Error())
+	})
+}
+
 func TestMerge(t *testing.T) {
 	assert := assert.New(t)