diff --git a/pdf/draw_test.go b/pdf/draw_test.go
index 643b29c..2874819 100644
--- a/pdf/draw_test.go
+++ b/pdf/draw_test.go
@@ -7,20 +7,16 @@ import (
 	"image/color"
 	"image/draw"
 	"image/png"
-	"io"
-	"log"
 	"os"
 	"os/exec"
 	"strings"
 	"testing"
 	"time"
 
-	"github.com/benoitkugler/go-weasyprint/pdf/test"
 	"github.com/benoitkugler/pdf/model"
 	"github.com/benoitkugler/webrender/backend"
 	"github.com/benoitkugler/webrender/html/document"
 	"github.com/benoitkugler/webrender/html/tree"
-	"github.com/benoitkugler/webrender/logger"
 	"github.com/benoitkugler/webrender/text"
 	"github.com/benoitkugler/webrender/utils"
 	tu "github.com/benoitkugler/webrender/utils/testutils"
@@ -47,16 +43,6 @@ var colorByName = map[byte]color.RGBA{
 	'z': joker,                            // unspecified, accepts anything
 }
 
-func init() {
-	logger.ProgressLogger.SetOutput(io.Discard)
-
-	var err error
-	fontconfig, err = test.LoadTestFontConfig("test/")
-	if err != nil {
-		log.Fatalf("creating font configuration: %s", err)
-	}
-}
-
 // convert a PDF file to an image using Ghostscript, and extract the pixels,
 // expecting a one color image
 func pdfToColor(img image.Image) (color.RGBA, error) {
diff --git a/pdf/pdf_test.go b/pdf/pdf_test.go
index 323a053..bd1f75e 100644
--- a/pdf/pdf_test.go
+++ b/pdf/pdf_test.go
@@ -5,6 +5,7 @@ import (
 	"crypto/md5"
 	"fmt"
 	"io"
+	"log"
 	"math"
 	"os"
 	"path/filepath"
@@ -14,16 +15,28 @@ import (
 	"strings"
 	"testing"
 
+	"github.com/benoitkugler/go-weasyprint/pdf/test"
 	"github.com/benoitkugler/pdf/model"
 	"github.com/benoitkugler/pdf/reader"
 	pdfParser "github.com/benoitkugler/pdf/reader/parser"
 	"github.com/benoitkugler/webrender/backend"
 	"github.com/benoitkugler/webrender/css/parser"
+	"github.com/benoitkugler/webrender/logger"
 	"github.com/benoitkugler/webrender/matrix"
 	"github.com/benoitkugler/webrender/utils"
 	"github.com/benoitkugler/webrender/utils/testutils"
 )
 
+func init() {
+	logger.ProgressLogger.SetOutput(io.Discard)
+
+	var err error
+	fontconfig, err = test.LoadTestFontConfig("test/")
+	if err != nil {
+		log.Fatalf("creating font configuration: %s", err)
+	}
+}
+
 func TestPaint(t *testing.T) {
 	c := NewOutput()
 	page := c.AddPage(0, 200, 100, 0)
diff --git a/pdf/test/utils.go b/pdf/test/utils.go
index c268e06..ab458c0 100644
--- a/pdf/test/utils.go
+++ b/pdf/test/utils.go
@@ -2,8 +2,8 @@ package test
 
 import (
 	"fmt"
-	"os"
 	"path/filepath"
+	"sync"
 
 	fc "github.com/benoitkugler/textprocessing/fontconfig"
 	"github.com/benoitkugler/textprocessing/pango/fcfonts"
@@ -11,25 +11,31 @@ import (
 	"github.com/benoitkugler/webrender/text"
 )
 
+var lock sync.Mutex
+
 // LoadTestFontConfig loads the font index in [cacheDir],
 // creating it if needed.
 func LoadTestFontConfig(cacheDir string) (text.FontConfiguration, error) {
+	lock.Lock()
+	defer lock.Unlock()
+
 	const cacheFile = "cache.fc"
 	cachePath := filepath.Join(cacheDir, cacheFile)
 
-	_, err := os.Stat(cachePath)
+	_, err := fc.LoadFontsetFile(cachePath)
 	if err != nil {
 		// build the index
 		fmt.Println("Scanning fonts...")
 		_, err := fc.ScanAndCache(cachePath)
 		if err != nil {
-			return nil, err
+			return nil, fmt.Errorf("scanning fonts: %s", err)
 		}
+		fmt.Println("Font index written in", cachePath)
 	}
 
 	fs, err := fc.LoadFontsetFile(cachePath)
 	if err != nil {
-		return nil, err
+		return nil, fmt.Errorf("reading font index: %s", err)
 	}
 
 	return text.NewFontConfigurationPango(fcfonts.NewFontMap(fc.Standard.Copy(), fs)), nil