diff --git a/ofdgo_reader.go b/ofdgo_reader.go
index 9cb2532..80b8af9 100644
--- a/ofdgo_reader.go
+++ b/ofdgo_reader.go
@@ -36,6 +36,7 @@ type Reader struct {
 	compositeGraphicUnitCache map[string]*CompositeGraphicUnit
 	doc                       *Document
 	Stamps                    map[string][]Stamp
+	fileIndex                 map[string]*zip.File
 }
 
 // Close 关闭阅读器
@@ -50,6 +51,10 @@ func (r *Reader) Close() error {
 // initRoot 读取根节点信息
 // 返回: error 错误信息
 func (r *Reader) initRoot() error {
+	r.fileIndex = make(map[string]*zip.File)
+	for _, f := range r.Zip.File {
+		r.fileIndex[f.Name] = f
+	}
 	data, err := r.readFile("OFD.xml")
 	if err != nil {
 		return fmt.Errorf("failed to read ofd.xml: %w", err)
@@ -72,10 +77,8 @@ func (r *Reader) initRoot() error {
 func (r *Reader) readFile(name string) ([]byte, error) {
 	name = strings.ReplaceAll(name, "\\", "/")
 	name = strings.TrimPrefix(name, "/")
-	for _, f := range r.Zip.File {
-		if f.Name == name {
-			return readZipFile(f)
-		}
+	if f, ok := r.fileIndex[name]; ok {
+		return readZipFile(f)
 	}
 	return nil, fmt.Errorf("file not found: %s", name)
 }
@@ -86,10 +89,8 @@ func (r *Reader) readFile(name string) ([]byte, error) {
 func (r *Reader) openFile(name string) (io.ReadCloser, error) {
 	name = strings.ReplaceAll(name, "\\", "/")
 	name = strings.TrimPrefix(name, "/")
-	for _, f := range r.Zip.File {
-		if f.Name == name {
-			return f.Open()
-		}
+	if f, ok := r.fileIndex[name]; ok {
+		return f.Open()
 	}
 	return nil, fmt.Errorf("file not found: %s", name)
 }
diff --git a/ofdgo_renderer.go b/ofdgo_renderer.go
index 70a6e39..7bd5cde 100644
--- a/ofdgo_renderer.go
+++ b/ofdgo_renderer.go
@@ -23,6 +23,7 @@ import (
 	"io/fs"
 	"math"
 	"path/filepath"
+	"runtime"
 	"strconv"
 	"strings"
 
@@ -777,18 +778,26 @@ func (r *Renderer) loadFont(fontID string) *canvas.FontFamily {
 				return ff
 			}
 		}
-		winFontDir := `C:\Windows\Fonts`
-		matches := r.globFontFiles(winFontDir, "*"+targetName+"*")
+		var sysFontDir string
+		switch runtime.GOOS {
+		case "linux":
+			sysFontDir = `/usr/share/fonts`
+		case "darwin":
+			sysFontDir = `/Library/Fonts`
+		default:
+			sysFontDir = `C:\Windows\Fonts`
+		}
+		matches := r.globFontFiles(sysFontDir, "*"+targetName+"*")
 		if len(matches) == 0 {
 			switch targetName {
 			case "SimSun":
-				matches = r.globFontFiles(winFontDir, "simsun.ttc")
+				matches = r.globFontFiles(sysFontDir, "simsun.ttc")
 			case "KaiTi":
-				matches = r.globFontFiles(winFontDir, "simkai.ttf")
+				matches = r.globFontFiles(sysFontDir, "simkai.ttf")
 			case "SimHei":
-				matches = r.globFontFiles(winFontDir, "simhei.ttf")
+				matches = r.globFontFiles(sysFontDir, "simhei.ttf")
 			case "FangSong":
-				matches = r.globFontFiles(winFontDir, "simfang.ttf")
+				matches = r.globFontFiles(sysFontDir, "simfang.ttf")
 			}
 		}
 		for _, m := range matches {
diff --git a/ofdgo_sign.go b/ofdgo_sign.go
index ce6b3f5..1b0bc29 100644
--- a/ofdgo_sign.go
+++ b/ofdgo_sign.go
@@ -71,28 +71,29 @@ func (r *Reader) parseSignatures(doc *Document) error {
 		return err
 	}
 	for _, sigRef := range signatures.List {
-		sigPath := path.Join(path.Dir(doc.Signatures), sigRef.BaseLoc)
-		sf, err := r.openFile(sigPath)
-		if err != nil {
-			continue
-		}
-		var sigFile SignatureFile
-		if err := xml.NewDecoder(sf).Decode(&sigFile); err != nil {
-			sf.Close()
-			continue
-		}
-		sf.Close()
-		signedValuePath := path.Join(path.Dir(sigPath), sigFile.SignedValue)
-		svData, err := r.ResData(signedValuePath)
-		if err != nil {
-			continue
-		}
-		sealType, sealData := extractSeal(svData)
-		for _, annot := range sigFile.SignedInfo.StampAnnot {
-			pageID := annot.PageRef
-			bbox, _ := ParseBox(annot.Boundary)
-			r.addStamp(pageID, bbox, sealType, sealData)
-		}
+		func(sigRef OFDSignature) {
+			sigPath := path.Join(path.Dir(doc.Signatures), sigRef.BaseLoc)
+			sf, err := r.openFile(sigPath)
+			if err != nil {
+				return
+			}
+			defer sf.Close()
+			var sigFile SignatureFile
+			if err := xml.NewDecoder(sf).Decode(&sigFile); err != nil {
+				return
+			}
+			signedValuePath := path.Join(path.Dir(sigPath), sigFile.SignedValue)
+			svData, err := r.ResData(signedValuePath)
+			if err != nil {
+				return
+			}
+			sealType, sealData := extractSeal(svData)
+			for _, annot := range sigFile.SignedInfo.StampAnnot {
+				pageID := annot.PageRef
+				bbox, _ := ParseBox(annot.Boundary)
+				r.addStamp(pageID, bbox, sealType, sealData)
+			}
+		}(sigRef)
 	}
 	return nil
 }