diff --git a/.gitignore b/.gitignore
index 2055b1e..03cd335 100644
--- a/.gitignore
+++ b/.gitignore
@@ -3,11 +3,5 @@
 *.swp
 **/.idea/workspace.xml
 **/.idea/tasks.xml
-bin
-*.exe
-*.dll
-*.so
-*.dylib
-*.test
-*.out
-.glide/
+*.pdf
+bin/
diff --git a/Makefile b/Makefile
index e10eb75..71c408f 100644
--- a/Makefile
+++ b/Makefile
@@ -6,11 +6,11 @@ clean:
 	rm -r bin/
 	go clean ./cmd/ecload/ ./pkg/ecload/
 
-bin/ecload:
+bin/ecload: cmd/ecload/*.go pkg/ecload/*.go
 	GOOS=linux GOARCH=amd64 go build -ldflags '-s' -v -o $@ cmd/ecload/main.go
 
-bin/ecload.exe:
+bin/ecload.exe: cmd/ecload/*.go pkg/ecload/*.go
 	GOOS=windows GOARCH=amd64 go build -ldflags '-s' -v -o $@ cmd/ecload/main.go
 
-bin/ecload-mac:
+bin/ecload-mac: cmd/ecload/*.go pkg/ecload/*.go
 	GOOS=darwin GOARCH=amd64 go build -ldflags '-s' -v -o $@ cmd/ecload/main.go
diff --git a/cmd/ecload/main.go b/cmd/ecload/main.go
index b74d9a4..b4da6c6 100644
--- a/cmd/ecload/main.go
+++ b/cmd/ecload/main.go
@@ -26,7 +26,7 @@ func initLogger(
 		Trace:   log.New(traceHandle, "TRACE: ", log.Ldate|log.Ltime),
 		Info:    log.New(infoHandle, "INFO: ", log.Ldate|log.Ltime),
 		Warning: log.New(warningHandle, "WARNING: ", log.Ldate|log.Ltime),
-		Error:   log.New(errorHandle, "ERROR: ", log.Ldate|log.Ltime),
+		Error:   log.New(errorHandle, "ERROR: ", log.Ldate|log.Ltime|log.Lshortfile),
 	}
 }
 
diff --git a/pkg/ecload/ecload.go b/pkg/ecload/ecload.go
index b1e17d7..4f21a90 100644
--- a/pkg/ecload/ecload.go
+++ b/pkg/ecload/ecload.go
@@ -14,6 +14,8 @@ import (
 	"sync"
 )
 
+const MAX_DOWNLOADS = 10
+
 const BASEURL = "https://www.e-codices.unifr.ch"
 const THUMBNAILURL = "%s/en/thumbs/%s"
 
@@ -36,16 +38,29 @@ func DownloadBook(outDir string, size string, id string, logger Logger) error {
 	defer os.RemoveAll(dir)
 
 	var wg sync.WaitGroup
+	semaphore := make(chan struct{}, MAX_DOWNLOADS)
 
 	logger.Info.Println("downloading pages...")
 	for index, pageUrl := range pageUrls {
-		downloadUrl, err:= getSizeLink(pageUrl, size)
-		if err != nil {
-			return err
-		}
+		wg.Add(1)
 
-		filename := fmt.Sprintf("%06d.jpg", index)
-		go downloadToFile(filename, dir, downloadUrl, wg)
+		go func(index int, pageUrl string) {
+			defer wg.Done()
+			semaphore <- struct{}{}
+
+			defer func() {
+				<-semaphore
+			}()
+
+			downloadUrl, err:= getSizeLink(pageUrl, size)
+			if err != nil {
+				//return err
+			}
+
+			filename := fmt.Sprintf("%06d.jpg", index)
+			downloadToFile(filename, dir, downloadUrl)
+
+		}(index, pageUrl)
 	}
 
 	wg.Wait()
@@ -58,7 +73,7 @@ func DownloadBook(outDir string, size string, id string, logger Logger) error {
 	pdfPath := path.Join(outDir, fmt.Sprintf("%s.pdf", strings.ReplaceAll(id, "/", "_")))
 	logger.Info.Printf("Saving pdf to %s...", pdfPath)
 
-	return ImgsToPdf(dir, pdfPath)
+	return ImgDirToPdf(dir, pdfPath)
 }
 
 // Find the download link for a page of a specific size.
diff --git a/pkg/ecload/fetcher.go b/pkg/ecload/fetcher.go
index 351f0ac..8bbcc54 100644
--- a/pkg/ecload/fetcher.go
+++ b/pkg/ecload/fetcher.go
@@ -11,7 +11,6 @@ import (
 	"net/http"
 	"os"
 	"path"
-	"sync"
 )
 
 // Download a html page from an url (must be UTF-8) and convert it to a goquery document.
@@ -35,10 +34,7 @@ func fetchDocument(url string) (*goquery.Document, error) {
 }
 
 // Download a file.
-func downloadToFile(filename string, dir string, pageUrl string, wg sync.WaitGroup) error {
-	wg.Add(1)
-	defer wg.Done()
-
+func downloadToFile(filename string, dir string, pageUrl string) error {
 	fullpath := path.Join(dir, filename)
 
 	out, err := os.Create(fullpath)
diff --git a/pkg/ecload/pdf.go b/pkg/ecload/pdf.go
index 9df75fd..b69907f 100644
--- a/pkg/ecload/pdf.go
+++ b/pkg/ecload/pdf.go
@@ -5,44 +5,41 @@
 package ecload
 
 import (
-	"image"
-	_ "image/jpeg"
 	"io/ioutil"
 	"os"
 	"path"
+	"strings"
 
 	"github.com/jung-kurt/gofpdf"
 )
 
 // Concatenate all jpg files in a directory to a single pdf.
-func ImgsToPdf(dir string, output string) error {
-	pdf := gofpdf.New("P", "mm", "", "")
-
+func ImgDirToPdf(dir string, output string) error {
 	files, err := ioutil.ReadDir(dir)
 	if err != nil {
 		return err
 	}
 
+	pdf := gofpdf.New("P", "mm", "", "")
+	opt := gofpdf.ImageOptions{ImageType: "jpg", ReadDpi: true}
+
 	for _, f := range files {
-		filepath := path.Join(dir, f.Name())
+		if strings.HasSuffix(f.Name(), ".jpg") {
+			filepath := path.Join(dir, f.Name())
 
-		reader, err := os.Open(filepath)
-		if err != nil {
-			return err
+			reader, err := os.Open(filepath)
+			if err != nil {
+				return err
+			}
+
+			pdf.RegisterImageOptionsReader(f.Name(), opt, reader)
+			info := pdf.RegisterImageOptions(f.Name(), opt)
+			pdf.AddPageFormat("P", gofpdf.SizeType{ Wd: info.Width(), Ht: info.Height() })
+
+			pdf.ImageOptions(f.Name(), 0, 0, info.Width(), info.Height(), false, opt, 0, "")
+
+			reader.Close()
 		}
-
-		img, _, err := image.DecodeConfig(reader)
-		if err != nil {
-			return err
-		}
-
-		pdf.AddPageFormat("P", gofpdf.SizeType{Wd: float64(img.Width), Ht: float64(img.Height)})
-
-		opt := gofpdf.ImageOptions{ImageType: "jpg", ReadDpi: true}
-		pdf.RegisterImageOptionsReader(f.Name(), opt, reader)
-		pdf.ImageOptions(f.Name(), 0, 0, 0, 0, false, opt, 0, "")
-
-		reader.Close()
 	}
 
 	return pdf.OutputFileAndClose(output)