diff --git a/formstream.go b/formstream.go
index fe30475..311fab7 100644
--- a/formstream.go
+++ b/formstream.go
@@ -57,24 +57,32 @@ const (
 	defaultMaxMemFileSize = 32 * MB
 )
 
+// WithMaxParts sets the maximum number of parts to be parsed.
+// default: 10000
 func WithMaxParts(maxParts uint) ParserOption {
 	return func(c *parserConfig) {
 		c.maxParts = maxParts
 	}
 }
 
+// WithMaxHeaders sets the maximum number of headers to be parsed.
+// default: 10000
 func WithMaxHeaders(maxHeaders uint) ParserOption {
 	return func(c *parserConfig) {
 		c.maxHeaders = maxHeaders
 	}
 }
 
+// WithMaxMemSize sets the maximum memory size to be used for parsing.
+// default: 32MB
 func WithMaxMemSize(maxMemSize DataSize) ParserOption {
 	return func(c *parserConfig) {
 		c.maxMemSize = maxMemSize
 	}
 }
 
+// WithMaxMemFileSize sets the maximum memory size to be used for parsing a file.
+// default: 32MB
 func WithMaxMemFileSize(maxMemFileSize DataSize) ParserOption {
 	return func(c *parserConfig) {
 		c.maxMemFileSize = maxMemFileSize
@@ -86,10 +94,12 @@ type Value struct {
 	header  Header
 }
 
+// Unwrap returns the content and header of the value.
 func (v Value) Unwrap() (string, Header) {
 	return string(v.content), v.header
 }
 
+// UnwrapRaw returns the raw content and header of the value.
 func (v Value) UnwrapRaw() ([]byte, Header) {
 	return v.content, v.header
 }
@@ -112,18 +122,26 @@ func newHeader(h textproto.MIMEHeader) Header {
 	}
 }
 
+// Get returns the first value associated with the given key.
+// If there are no values associated with the key, Get returns "".
 func (h Header) Get(key string) string {
 	return h.header.Get(key)
 }
 
+// ContentType returns the value of the "Content-Type" header field.
+// If there are no values associated with the key, ContentType returns "".
 func (h Header) ContentType() string {
 	return h.header.Get("Content-Type")
 }
 
+// Name returns the value of the "name" parameter in the "Content-Disposition" header field.
+// If there are no values associated with the key, Name returns "".
 func (h Header) Name() string {
 	return h.dispositionParams["name"]
 }
 
+// FileName returns the value of the "filename" parameter in the "Content-Disposition" header field.
+// If there are no values associated with the key, FileName returns "".
 func (h Header) FileName() string {
 	return h.dispositionParams["filename"]
 }
diff --git a/formstream_test.go b/formstream_test.go
index ca6b40c..1e7aa95 100644
--- a/formstream_test.go
+++ b/formstream_test.go
@@ -118,8 +118,10 @@ func createSampleForm(w io.Writer, fileSize formstream.DataSize, boundary string
 	if err != nil {
 		return fmt.Errorf("failed to create part: %w", err)
 	}
+
+	mbData := make([]byte, formstream.MB)
 	for i := 0; i < int(fileSize/formstream.MB); i++ {
-		_, err := pw.Write([]byte(strings.Repeat("a", int(formstream.MB))))
+		_, err := pw.Write(mbData)
 		if err != nil {
 			return fmt.Errorf("failed to write: %w", err)
 		}
diff --git a/parse.go b/parse.go
index 5d4b478..51387bb 100644
--- a/parse.go
+++ b/parse.go
@@ -21,6 +21,7 @@ var (
 	ErrTooLargeForm = errors.New("too large form")
 )
 
+// Parse parses the multipart form from r.
 func (p *Parser) Parse(r io.Reader) (err error) {
 	hsc := newHookSatisfactionChecker(p.hookMap, &p.parserConfig)
 	defer func() {
diff --git a/register.go b/register.go
index ae2399b..2e726a5 100644
--- a/register.go
+++ b/register.go
@@ -4,6 +4,7 @@ import (
 	"fmt"
 )
 
+// Register registers a stream hook with the given name.
 func (p *Parser) Register(name string, fn StreamHookFunc, options ...RegisterOption) error {
 	if _, ok := p.hookMap[name]; ok {
 		return DuplicateHookNameError{Name: name}
@@ -36,6 +37,7 @@ type registerConfig struct {
 
 type RegisterOption func(*registerConfig)
 
+// WithRequiredPart sets the required part names for the stream hook.
 func WithRequiredPart(name string) RegisterOption {
 	return func(c *registerConfig) {
 		c.requireParts = append(c.requireParts, name)