diff --git a/go.mod b/go.mod
index aec5608..db6d212 100644
--- a/go.mod
+++ b/go.mod
@@ -3,7 +3,7 @@ module github.com/go-text/typesetting
 go 1.17
 
 require (
-	github.com/go-text/typesetting-utils v0.0.0-20231211103740-d9332ae51f04
+	github.com/go-text/typesetting-utils v0.0.0-20240317173224-1986cbe96c66
 	golang.org/x/image v0.3.0
 	golang.org/x/text v0.9.0
 )
diff --git a/go.sum b/go.sum
index b1138d0..4534de2 100644
--- a/go.sum
+++ b/go.sum
@@ -2,6 +2,8 @@ github.com/go-text/typesetting-utils v0.0.0-20231204162240-fa4dc564ba79 h1:3yBOz
 github.com/go-text/typesetting-utils v0.0.0-20231204162240-fa4dc564ba79/go.mod h1:DDxDdQEnB70R8owOx3LVpEFvpMK9eeH1o2r0yZhFI9o=
 github.com/go-text/typesetting-utils v0.0.0-20231211103740-d9332ae51f04 h1:zBx+p/W2aQYtNuyZNcTfinWvXBQwYtDfme051PR/lAY=
 github.com/go-text/typesetting-utils v0.0.0-20231211103740-d9332ae51f04/go.mod h1:DDxDdQEnB70R8owOx3LVpEFvpMK9eeH1o2r0yZhFI9o=
+github.com/go-text/typesetting-utils v0.0.0-20240317173224-1986cbe96c66 h1:GUrm65PQPlhFSKjLPGOZNPNxLCybjzjYBzjfoBGaDUY=
+github.com/go-text/typesetting-utils v0.0.0-20240317173224-1986cbe96c66/go.mod h1:DDxDdQEnB70R8owOx3LVpEFvpMK9eeH1o2r0yZhFI9o=
 github.com/yuin/goldmark v1.4.13/go.mod h1:6yULJ656Px+3vBD8DxQVa3kxgyrAnzto9xy5taEt/CY=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
 golang.org/x/crypto v0.0.0-20210921155107-089bfa567519/go.mod h1:GvvjBRRGRdwPK5ydBHafDWAxML/pGHZbMvKqRZ5+Abc=
diff --git a/harfbuzz/fonts_test.go b/harfbuzz/fonts_test.go
index 8b7623c..3d12843 100644
--- a/harfbuzz/fonts_test.go
+++ b/harfbuzz/fonts_test.go
@@ -5,6 +5,7 @@ import (
 	"reflect"
 	"testing"
 
+	"github.com/go-text/typesetting/language"
 	"github.com/go-text/typesetting/opentype/api/font"
 	tu "github.com/go-text/typesetting/opentype/testutils"
 )
@@ -259,3 +260,16 @@ func TestNames(t *testing.T) {
 	/* beyond last glyph */
 	tu.Assert(t, ft.GlyphName(2000) == "")
 }
+
+func TestUnifont(t *testing.T) {
+	// https://github.com/go-text/typesetting/issues/140
+	ft := openFontFileTT(t, "bitmap/unifont-15.1.05.otf")
+
+	buf := NewBuffer()
+	buf.Props.Language = "en-us"
+	buf.Props.Script = language.Latin
+	buf.Props.Direction = LeftToRight
+	buf.AddRunes([]rune{'a'}, 0, 1)
+	font := NewFont(&font.Face{Font: ft})
+	buf.Shape(font, nil) // just check for crashes
+}
diff --git a/opentype/api/font/ot_layout.go b/opentype/api/font/ot_layout.go
index 848ab62..43e641d 100644
--- a/opentype/api/font/ot_layout.go
+++ b/opentype/api/font/ot_layout.go
@@ -12,11 +12,18 @@ type Layout struct {
 }
 
 func newLayout(table tables.Layout) Layout {
+	fCount := len(table.FeatureList.Features)
 	out := Layout{
 		Scripts:  make([]Script, len(table.ScriptList.Scripts)),
-		Features: make([]Feature, len(table.FeatureList.Features)),
+		Features: make([]Feature, fCount),
 	}
 	for i, s := range table.ScriptList.Scripts {
+		if langSys := s.DefaultLangSys; langSys != nil {
+			sanitizeLangSys(langSys, fCount)
+		}
+		for i := range s.LangSys {
+			sanitizeLangSys(&s.LangSys[i], fCount)
+		}
 		out.Scripts[i] = Script{
 			Script: s,
 			Tag:    table.ScriptList.Records[i].Tag,
@@ -34,6 +41,13 @@ func newLayout(table tables.Layout) Layout {
 	return out
 }
 
+func sanitizeLangSys(langSys *tables.LangSys, featuresCount int) {
+	if int(langSys.RequiredFeatureIndex) >= featuresCount {
+		// invalid index : replace it by the sentinel value
+		langSys.RequiredFeatureIndex = 0xFFFF
+	}
+}
+
 type Script struct {
 	tables.Script
 	Tag Tag