diff --git a/Makefile b/Makefile
index 091703b3d..b56bee351 100644
--- a/Makefile
+++ b/Makefile
@@ -49,7 +49,6 @@ release: clean dirty_worktree_check dist/linux_amd64/baur dist/darwin_amd64/baur
 	@echo - git push --tags
 	@echo - upload $(ls dist/*/*.tar.xz) files
 
-
 .PHONY: check
 check:
 	$(info * running static code checks)
diff --git a/command/apps_builds.go b/command/apps_builds.go
index 8ae0c945a..6b3a71440 100644
--- a/command/apps_builds.go
+++ b/command/apps_builds.go
@@ -120,7 +120,7 @@ func resultAddUploadResult(appName string, ar baur.BuildOutput, r *upload.Result
 
 	b, exist := result[appName]
 	if !exist {
-		log.Fatalf("resultAddUploadResult: %q does not exist in build result map\n", appName)
+		log.Fatalf("resultAddUploadResult: %q does not exist in build result map", appName)
 	}
 
 	if r.Job.Type() == upload.JobDocker {
@@ -131,12 +131,12 @@ func resultAddUploadResult(appName string, ar baur.BuildOutput, r *upload.Result
 
 	artDigest, err := ar.Digest()
 	if err != nil {
-		log.Fatalf("getting digest for output %q failed: %s\n", ar, err)
+		log.Fatalf("getting digest for output %q failed: %s", ar, err)
 	}
 
 	arSize, err := ar.Size(&outputBackends)
 	if err != nil {
-		log.Fatalf("getting size of output %q failed: %s\n", ar, err)
+		log.Fatalf("getting size of output %q failed: %s", ar, err)
 	}
 
 	b.Outputs = append(b.Outputs, &storage.Output{
@@ -157,7 +157,7 @@ func recordResultIsComplete(app *baur.App) (bool, *storage.Build) {
 
 	b, exist := result[app.Name]
 	if !exist {
-		log.Fatalf("recordResultIfComplete: %q does not exist in build result map\n", app.Name)
+		log.Fatalf("recordResultIfComplete: %q does not exist in build result map", app.Name)
 	}
 
 	if len(app.Outputs) == len(b.Outputs) {
@@ -192,7 +192,7 @@ func calcDigests(app *baur.App) ([]*storage.Input, string) {
 	// The storageInputs can be removed, apps.BuildInputs() can be used
 	// instead to later fill the struct for the db
 
-	log.Debugf("%s: resolving build inputs and calculating digests...\n", app)
+	log.Debugf("%s: resolving build inputs and calculating digests...", app)
 	buildInputs, err := app.BuildInputs()
 	if err != nil {
 		log.Fatalf("%s: resolving build input paths failed: %s\n", app, err)
@@ -201,7 +201,7 @@ func calcDigests(app *baur.App) ([]*storage.Input, string) {
 	for _, s := range buildInputs {
 		d, err := s.Digest()
 		if err != nil {
-			log.Fatalf("%s: calculating build input digest failed: %s\n", app, err)
+			log.Fatalf("%s: calculating build input digest failed: %s", app, err)
 		}
 
 		storageInputs = append(storageInputs, &storage.Input{
@@ -215,7 +215,7 @@ func calcDigests(app *baur.App) ([]*storage.Input, string) {
 	if len(inputDigests) > 0 {
 		td, err := sha384.Sum(inputDigests)
 		if err != nil {
-			log.Fatalln("calculating total input digest failed:", err)
+			log.Fatalf("%s: calculating total input digest failed: %s", app, err)
 		}
 
 		totalDigest = td.String()
@@ -247,14 +247,14 @@ func createBuildJobs(apps []*baur.App) []*build.Job {
 
 func startBGUploader(outputCnt int, uploadChan chan *upload.Result) upload.Manager {
 	var dockerUploader *docker.Client
-	s3Uploader, err := s3.NewClient()
+	s3Uploader, err := s3.NewClient(log.StdLogger)
 	if err != nil {
 		log.Fatalln(err.Error())
 	}
 
 	dockerUser, dockerPass := dockerAuthFromEnv()
 	if len(dockerUser) != 0 {
-		log.Debugf("read docker registry auth data from %q, %q Env variables, authenticating as %q \n",
+		log.Debugf("read docker registry auth data from %q, %q Env variables, authenticating as %q",
 			dockerEnvUsernameVar, dockerEnvPasswordVar, dockerUser)
 		dockerUploader, err = docker.NewClientwAuth(dockerUser, dockerPass)
 	} else {
@@ -264,7 +264,7 @@ func startBGUploader(outputCnt int, uploadChan chan *upload.Result) upload.Manag
 		log.Fatalln(err)
 	}
 
-	uploader := sequploader.New(s3Uploader, dockerUploader, uploadChan)
+	uploader := sequploader.New(log.StdLogger, s3Uploader, dockerUploader, uploadChan)
 
 	outputBackends.DockerClt = dockerUploader
 
@@ -304,7 +304,7 @@ func waitPrintUploadStatus(uploader upload.Manager, uploadChan chan *upload.Resu
 			log.Fatalf("upload of %q failed: %s\n", ud.Output, res.Err)
 		}
 
-		log.Actionf("%s: %s uploaded to %s (%.3fs)\n",
+		fmt.Printf("%s: %s uploaded to %s (%.3fs)\n",
 			ud.App.Name, ud.Output.LocalPath(), res.URL, res.Duration.Seconds())
 
 		resultAddUploadResult(ud.App.Name, ud.Output, res)
@@ -315,7 +315,7 @@ func waitPrintUploadStatus(uploader upload.Manager, uploadChan chan *upload.Resu
 			if err := store.Save(build); err != nil {
 				log.Fatalf("storing build information about %q failed: %s", ud.App.Name, err)
 			}
-			log.Infof("%s: build %d stored in database\n", ud.App.Name, build.ID)
+			fmt.Printf("%s: build %d stored in database\n", ud.App.Name, build.ID)
 
 			log.Debugf("stored the following build information: %s\n", prettyprint.AsString(build))
 		}
@@ -341,14 +341,14 @@ func outstandingBuilds(storage storage.Storer, apps []*baur.App) []*baur.App {
 			res = append(res, app)
 		}
 
-		if !log.DebugEnabled {
+		if !verboseFlag {
 			fmt.Printf(".")
 		}
 
 		log.Debugf("\n%s: build status. %q\n", app, buildStatus)
 	}
 
-	if !log.DebugEnabled {
+	if !log.DebugEnabled() {
 		fmt.Println()
 	}
 
@@ -370,15 +370,18 @@ func appBuildRun(cmd *cobra.Command, args []string) {
 	}
 
 	if !buildForce {
-		log.Actionf("identifying applications with outstanding builds")
+		fmt.Printf("identifying applications with outstanding builds")
+		if verboseFlag {
+			fmt.Println()
+		}
 		apps = outstandingBuilds(store, apps)
 	}
 
 	if len(apps) == 0 {
 		fmt.Println()
 		term.PrintSep()
-		fmt.Printf("Application build(s) already exist, nothing to build, see 'baur ls -b'.\n" +
-			"If you want to rebuild applications pass '-f' to 'baur build'\n")
+		fmt.Println("Application build(s) already exist, nothing to build, see 'baur ls -b'.\n" +
+			"If you want to rebuild applications pass '-f' to 'baur build'")
 		os.Exit(0)
 	}
 
@@ -397,10 +400,10 @@ func appBuildRun(cmd *cobra.Command, args []string) {
 		uploadWatchFin = make(chan struct{}, 1)
 		go waitPrintUploadStatus(uploader, uploadChan, uploadWatchFin, outputCnt)
 
-		log.Actionf("building and uploading the following applications: \n%s\n",
+		fmt.Printf("building and uploading the following applications:\n%s\n",
 			appsToString(apps))
 	} else {
-		log.Actionf("building the following applications: \n%s\n",
+		fmt.Printf("building the following applications:\n%s\n",
 			appsToString(apps))
 	}
 
@@ -413,28 +416,29 @@ func appBuildRun(cmd *cobra.Command, args []string) {
 		app := bud.App
 
 		if status.Error != nil {
-			log.Fatalf("%s: build failed: %s\n", app.Name, status.Error)
+			log.Fatalf("%s: build failed: %s", app.Name, status.Error)
 		}
 
 		if status.ExitCode != 0 {
 			log.Fatalf("%s: build failed: command (%q) exited with code %d "+
-				"Output: %s\n",
+				"Output: %s",
 				app.Name, status.Job.Command, status.ExitCode, status.Output)
 		}
 
-		log.Actionf("%s: build successful (%.3fs)\n", app.Name, status.StopTs.Sub(status.StartTs).Seconds())
+		fmt.Printf("%s: build successful (%.3fs)\n", app.Name, status.StopTs.Sub(status.StartTs).Seconds())
 		resultAddBuildResult(bud, status)
 
 		for _, ar := range app.Outputs {
 			if !ar.Exists() {
-				log.Fatalf("build output %q of %s did not exist after build\n",
-					ar, app)
+				log.Fatalf("%s: build output %q did not exist after build",
+					app, ar)
 			}
 
 			if buildUpload {
 				uj, err := ar.UploadJob()
 				if err != nil {
-					log.Fatalf("could not get upload job for build output %s: %s", ar, err)
+					log.Fatalf("%s: could not get upload job for build output %s: %s",
+						app, ar, err)
 				}
 
 				uj.SetUserData(&uploadUserData{
@@ -447,22 +451,22 @@ func appBuildRun(cmd *cobra.Command, args []string) {
 			}
 			d, err := ar.Digest()
 			if err != nil {
-				log.Fatalf("%s: could determine input digest of %s: %s\n",
+				log.Fatalf("%s: calculating input digest of %s failed: %s",
 					app.Name, ar, err)
 			}
 
-			log.Actionf("%s: created %s (%s)\n", app.Name, ar, d)
+			fmt.Printf("%s: created %s (%s)\n", app.Name, ar, d)
 		}
 
 	}
 
 	if buildUpload && outputCnt > 0 {
-		log.Actionf("waiting for uploads to finish...\n")
+		fmt.Println("waiting for uploads to finish...")
 		<-uploadWatchFin
 	}
 
 	term.PrintSep()
-	log.Infof("finished in %s\n", time.Since(startTs))
+	fmt.Printf("finished in %s\n", time.Since(startTs))
 }
 
 func mustGetBuildStatus(app *baur.App, storage storage.Storer) (baur.BuildStatus, *storage.Build, string) {
@@ -470,7 +474,7 @@ func mustGetBuildStatus(app *baur.App, storage storage.Storer) (baur.BuildStatus
 
 	status, build, err := baur.GetBuildStatus(storage, app)
 	if err != nil {
-		log.Fatalf("evaluating build status of %s failed: %s\n", app, err)
+		log.Fatalf("%s: evaluating build status of failed: %s", app, err)
 	}
 
 	if build != nil {
diff --git a/command/apps_init.go b/command/apps_init.go
index 57438b567..3b227edc6 100644
--- a/command/apps_init.go
+++ b/command/apps_init.go
@@ -1,6 +1,7 @@
 package command
 
 import (
+	"fmt"
 	"os"
 	"path"
 	"strings"
@@ -58,6 +59,6 @@ func appsInit(cmd *cobra.Command, args []string) {
 		log.Fatalln(err)
 	}
 
-	log.Infof("configuration file for %s was written to %s\n",
+	fmt.Printf("configuration file for %s was written to %s\n",
 		appName, baur.AppCfgFile)
 }
diff --git a/command/builds_verify.go b/command/builds_verify.go
index 148421412..909bd0add 100644
--- a/command/builds_verify.go
+++ b/command/builds_verify.go
@@ -62,7 +62,7 @@ func verify(cmd *cobra.Command, args []string) {
 	const dateLayout = "2006.01.02"
 	startTs, err := time.Parse(dateLayout, verifyFromDate)
 	if err != nil {
-		log.Fatalf("parsing start date value failed: %s\n:", err)
+		log.Fatalf("parsing start date value failed: %s:", err)
 	}
 	repo := MustFindRepository()
 
@@ -78,7 +78,7 @@ func verify(cmd *cobra.Command, args []string) {
 		log.Fatalln("retrieving applications from storage failed:", err)
 	}
 
-	log.Actionf("scanning for builds after %s with same inputs that produced different outputs...\n", startTs.Format(dateLayout))
+	fmt.Printf("scanning for builds after %s with same inputs that produced different outputs...\n", startTs.Format(dateLayout))
 
 	var issuesFound bool
 	for _, app := range storedApps {
diff --git a/command/helpers.go b/command/helpers.go
index b8b4f78d8..e5fb79350 100644
--- a/command/helpers.go
+++ b/command/helpers.go
@@ -28,14 +28,14 @@ func MustFindRepository() *baur.Repository {
 	if err != nil {
 		if os.IsNotExist(err) {
 			log.Fatalf("could not find repository root config file "+
-				"ensure the file '%s' exist in the root\n",
+				"ensure the file '%s' exist in the root",
 				baur.RepositoryCfgFile)
 		}
 
 		log.Fatalln(err)
 	}
 
-	log.Debugf("repository root found: %v\n", rep.Path)
+	log.Debugf("repository root found: %s", rep.Path)
 
 	return rep
 }
@@ -54,7 +54,7 @@ func mustArgToApp(repo *baur.Repository, arg string) *baur.App {
 	if isAppDir(arg) {
 		app, err := repo.AppByDir(arg)
 		if err != nil {
-			log.Fatalf("could not find application in dir '%s': %s\n", arg, err)
+			log.Fatalf("could not find application in dir '%s': %s", arg, err)
 		}
 
 		return app
@@ -63,7 +63,7 @@ func mustArgToApp(repo *baur.Repository, arg string) *baur.App {
 	app, err := repo.AppByName(arg)
 	if err != nil {
 		if os.IsNotExist(err) {
-			log.Fatalf("could not find application with name '%s'\n", arg)
+			log.Fatalf("could not find application with name '%s'", arg)
 		}
 		log.Fatalln(err)
 	}
@@ -75,7 +75,7 @@ func mustArgToApp(repo *baur.Repository, arg string) *baur.App {
 func MustGetPostgresClt(r *baur.Repository) *postgres.Client {
 	clt, err := postgres.New(r.PSQLURL)
 	if err != nil {
-		log.Fatalf("could not establish connection to postgreSQL db: %s\n", err)
+		log.Fatalf("could not establish connection to postgreSQL db: %s", err)
 	}
 
 	return clt
@@ -119,7 +119,7 @@ func mustArgToApps(repo *baur.Repository, args []string) []*baur.App {
 		}
 
 		if len(apps) == 0 {
-			log.Fatalf("could not find any applications\n"+
+			log.Fatalf("could not find any applications"+
 				"- ensure the [Discover] section is correct in %s\n"+
 				"- ensure that you have >1 application dirs "+
 				"containing a %s file\n",
diff --git a/command/inputs_show.go b/command/inputs_show.go
index 8b280e26a..309e01fbe 100644
--- a/command/inputs_show.go
+++ b/command/inputs_show.go
@@ -50,7 +50,7 @@ func inputsShow(cmd *cobra.Command, args []string) {
 	writeHeaders := !inputsShowConfig.quiet && !inputsShowConfig.csv
 
 	if len(app.BuildInputPaths) == 0 {
-		log.Fatalf("No build inputs have been configured in the %s file of %s\n", baur.AppCfgFile, app.Name)
+		log.Fatalf("No build inputs are configured in %s of %s", baur.AppCfgFile, app.Name)
 	}
 
 	if writeHeaders {
diff --git a/command/repo_init.go b/command/repo_init.go
index 5a9bc31a2..940f794d9 100644
--- a/command/repo_init.go
+++ b/command/repo_init.go
@@ -1,6 +1,7 @@
 package command
 
 import (
+	"fmt"
 	"os"
 	"path"
 
@@ -24,7 +25,7 @@ var initCmd = &cobra.Command{
 func initRepositoryCfg(cmd *cobra.Command, args []string) {
 	rep, err := baur.FindRepository()
 	if err == nil {
-		log.Fatalf("repository configuration %s already exist\n",
+		log.Fatalf("repository configuration %s already exist",
 			path.Join(rep.Path, baur.RepositoryCfgFile))
 	}
 
@@ -44,6 +45,6 @@ func initRepositoryCfg(cmd *cobra.Command, args []string) {
 		log.Fatalln(err)
 	}
 
-	log.Infof("written example repository configuration to %s\n",
+	fmt.Printf("written example repository configuration to %s\n",
 		baur.RepositoryCfgFile)
 }
diff --git a/command/root.go b/command/root.go
index 6885754b6..a5b45af04 100644
--- a/command/root.go
+++ b/command/root.go
@@ -8,6 +8,7 @@ import (
 
 	"github.com/spf13/cobra"
 
+	"github.com/simplesurance/baur/exec"
 	"github.com/simplesurance/baur/log"
 	"github.com/simplesurance/baur/version"
 )
@@ -25,7 +26,10 @@ var cpuProfilingFlag bool
 var defCPUProfFile = filepath.Join(os.TempDir(), "baur-cpu.prof")
 
 func initSb(_ *cobra.Command, _ []string) {
-	log.DebugEnabled = verboseFlag
+	if verboseFlag {
+		log.StdLogger.EnableDebug(verboseFlag)
+		exec.SetDebugOutputFn(log.StdLogger.Debugf)
+	}
 
 	if cpuProfilingFlag {
 		cpuProfFile, err := os.Create(defCPUProfFile)
@@ -50,7 +54,7 @@ func Execute() {
 	}
 
 	if cpuProfilingFlag {
-		log.Infof("\ncpu profile written to %q\n", defCPUProfFile)
+		fmt.Printf("\ncpu profile written to %q\n", defCPUProfFile)
 		pprof.StopCPUProfile()
 	}
 }
diff --git a/docker/docker.go b/docker/docker.go
index 8edc42265..3fb6d452d 100644
--- a/docker/docker.go
+++ b/docker/docker.go
@@ -12,8 +12,6 @@ import (
 	"docker.io/go-docker"
 	"docker.io/go-docker/api/types"
 	"github.com/pkg/errors"
-
-	"github.com/simplesurance/baur/log"
 )
 
 // Client is a docker client
@@ -110,10 +108,6 @@ func (c *Client) Upload(ctx context.Context, image, dest string) (string, error)
 	r := bufio.NewReader(closer)
 	for {
 		status, err := r.ReadBytes('\n')
-
-		log.Debugf("docker Upload of %s to %s, read server response: %q\n",
-			image, dest, status)
-
 		if err == io.EOF {
 			break
 		}
diff --git a/exec/exec.go b/exec/exec.go
index 683fef2c9..a585a1d11 100644
--- a/exec/exec.go
+++ b/exec/exec.go
@@ -7,15 +7,20 @@ import (
 	"syscall"
 
 	"github.com/pkg/errors"
-
-	"github.com/simplesurance/baur/log"
 )
 
+var debugOutputFn = func(string, ...interface{}) { return }
+
+// SetDebugOutputFn configures the package to pass debug output to this function
+func SetDebugOutputFn(fn func(format string, v ...interface{})) {
+	debugOutputFn = fn
+}
+
 // Command runs the passed command in a shell in the passed dir.
 // If the command exits with a code != 0, err is nil
 func Command(dir, command string) (output string, exitCode int, err error) {
 	cmd := exec.Command("sh", "-c", command)
-	log.Debugf("running in %q \"%s %s\"\n", dir, cmd.Path, strings.Join(cmd.Args, " "))
+	debugOutputFn("running in %q \"%s %s\"\n", dir, cmd.Path, strings.Join(cmd.Args, " "))
 
 	outReader, err := cmd.StdoutPipe()
 	if err != nil {
@@ -34,7 +39,7 @@ func Command(dir, command string) (output string, exitCode int, err error) {
 	in := bufio.NewScanner(outReader)
 	for in.Scan() {
 		o := in.Text()
-		log.Debugln(o)
+		debugOutputFn(o)
 		output += o + "\n"
 	}
 
diff --git a/gosrcdir.go b/gosrcdir.go
index 545efe506..609464f7d 100644
--- a/gosrcdir.go
+++ b/gosrcdir.go
@@ -9,7 +9,6 @@ import (
 
 	"github.com/simplesurance/baur/fs"
 	"github.com/simplesurance/baur/golang"
-	"github.com/simplesurance/baur/log"
 )
 
 // GoSrcDirs resolves Golang source files in directories to files including
@@ -51,8 +50,6 @@ func (g *GoSrcDirs) Resolve() ([]BuildInput, error) {
 		fullpaths = append(fullpaths, absPath)
 	}
 
-	log.Debugf("resolving go src files, GOPATH=%q, srcdirs=%q\n", g.gopath, fullpaths)
-
 	absSrcPaths, err := golang.SrcFiles(g.gopath, fullpaths...)
 	if err != nil {
 		return nil, err
diff --git a/log/log.go b/log/log.go
index b4d210725..72500ad4e 100644
--- a/log/log.go
+++ b/log/log.go
@@ -2,119 +2,149 @@ package log
 
 import (
 	"fmt"
+	"log"
 	"os"
-	"sync"
 )
 
-var lock = sync.Mutex{}
-
-// DebugEnabled set to true to print debug message otherwise they are suppressed
-var DebugEnabled bool
-
-const actionPrefix = "*"
 const errorPrefix = "ERROR"
 
-// Actionln prints something with the ActionPrefix preprended
-func Actionln(v ...interface{}) {
-	lock.Lock()
-	defer lock.Unlock()
+// Logger logs messages
+type Logger struct {
+	debugEnabled bool
+	logger       *log.Logger
+}
 
-	if len(v) != 0 {
-		v[0] = fmt.Sprintf("%s %s", actionPrefix, v[0])
-	}
+// StdLogger is the logger that is used from the log functions in this package
+var StdLogger = New(false)
 
-	fmt.Println(v...)
+// New returns a new Logger that logs to Stderr.
+// Debug messages are only printed if debugEnabled is true
+func New(debugEnabled bool) *Logger {
+	return &Logger{
+		debugEnabled: debugEnabled,
+		logger:       log.New(os.Stderr, "", 0),
+	}
 }
 
-// Actionf prints something with the ActionPrefix preprended
-func Actionf(format string, v ...interface{}) {
-	lock.Lock()
-	defer lock.Unlock()
+// EnableDebug enables/disables logging debug messages
+func (l *Logger) EnableDebug(enabled bool) {
+	l.debugEnabled = enabled
+}
 
-	fmt.Printf(actionPrefix+" "+format, v...)
+// DebugEnabled returns true if logging debug messages is enabled
+func (l *Logger) DebugEnabled() bool {
+	return l.debugEnabled
 }
 
 // Debugln logs a debug message to stdout.
 // It's only shown if debugging is enabled.
-func Debugln(v ...interface{}) {
-	lock.Lock()
-	defer lock.Unlock()
-
-	if !DebugEnabled {
+func (l *Logger) Debugln(v ...interface{}) {
+	if !l.debugEnabled {
 		return
 	}
 
-	fmt.Println(v...)
+	l.logger.Println(v...)
 }
 
 // Debugf logs a debug message to stdout.
 // It's only shown if debugging is enabled.
-func Debugf(format string, v ...interface{}) {
-	lock.Lock()
-	defer lock.Unlock()
-
-	if !DebugEnabled {
+func (l *Logger) Debugf(format string, v ...interface{}) {
+	if !l.debugEnabled {
 		return
 	}
 
-	fmt.Printf(format, v...)
+	l.logger.Printf(format, v...)
 }
 
 // Fatalln logs a message to stderr and terminates the application with an error
-func Fatalln(v ...interface{}) {
-	lock.Lock()
-	defer lock.Unlock()
-
+func (l *Logger) Fatalln(v ...interface{}) {
 	if len(v) != 0 {
 		v[0] = fmt.Sprintf("%s: %s", errorPrefix, v[0])
 	}
 
-	fmt.Fprintln(os.Stderr, v...)
-
-	os.Exit(1)
+	l.logger.Fatalln(v...)
 }
 
 // Fatalf logs a message to stderr and terminates the application with an error
-func Fatalf(format string, v ...interface{}) {
-	lock.Lock()
-	defer lock.Unlock()
-
-	fmt.Fprintf(os.Stderr, errorPrefix+": "+format, v...)
-	os.Exit(1)
+func (l *Logger) Fatalf(format string, v ...interface{}) {
+	l.logger.Fatalf(errorPrefix+": "+format, v...)
 }
 
 // Errorln logs a message to stderr
-func Errorln(v ...interface{}) {
-	lock.Lock()
-	defer lock.Unlock()
-
+func (l *Logger) Errorln(v ...interface{}) {
 	if len(v) != 0 {
 		v[0] = fmt.Sprintf("%s: %s", errorPrefix, v[0])
 	}
 
-	fmt.Fprintln(os.Stderr, v...)
+	l.logger.Println(v...)
 }
 
 // Errorf logs a message to stderr
-func Errorf(format string, v ...interface{}) {
-	lock.Lock()
-	defer lock.Unlock()
+func (l *Logger) Errorf(format string, v ...interface{}) {
+	l.logger.Printf(errorPrefix+": "+format, v...)
+}
+
+// Infoln logs a message to stdout
+/*
+func (l *Logger) Infoln(v ...interface{}) {
+	l.logger.Println(v...)
+}
+*/
+
+// Infof logs a message to stdout
+/*
+func (l *Logger) Infof(format string, v ...interface{}) {
+	l.logger.Printf(format, v...)
+}
+*/
+
+// DebugEnabled returns true if the Stdlogger logs debug messages
+func DebugEnabled() bool {
+	return StdLogger.DebugEnabled()
+}
+
+// Debugln logs a debug message to stdout.
+// It's only shown if debugging is enabled.
+func Debugln(v ...interface{}) {
+	StdLogger.Debugln(v...)
+}
+
+// Debugf logs a debug message to stdout.
+// It's only shown if debugging is enabled.
+func Debugf(format string, v ...interface{}) {
+	StdLogger.Debugf(format, v...)
+}
 
-	fmt.Fprintf(os.Stderr, errorPrefix+": "+format, v...)
+// Fatalln logs a message to stderr and terminates the application with an error
+func Fatalln(v ...interface{}) {
+	StdLogger.Fatalln(v...)
+}
+
+// Fatalf logs a message to stderr and terminates the application with an error
+func Fatalf(format string, v ...interface{}) {
+	StdLogger.Fatalf(format, v...)
+}
+
+// Errorln logs a message to stderr
+func Errorln(v ...interface{}) {
+	StdLogger.Errorln(v...)
+}
+
+// Errorf logs a message to stderr
+func Errorf(format string, v ...interface{}) {
+	StdLogger.Errorf(format, v...)
 }
 
 // Infoln logs a message to stdout
+/*
 func Infoln(v ...interface{}) {
-	lock.Lock()
-	defer lock.Unlock()
-
-	fmt.Println(v...)
+	StdLogger.Infoln(v...)
 }
+*/
 
 // Infof logs a message to stdout
+/*
 func Infof(format string, v ...interface{}) {
-	lock.Lock()
-	defer lock.Unlock()
-
-	fmt.Printf(format, v...)
+	StdLogger.Infof(format, v...)
 }
+*/
diff --git a/log/s3.go b/log/s3.go
deleted file mode 100644
index b6c298b11..000000000
--- a/log/s3.go
+++ /dev/null
@@ -1,9 +0,0 @@
-package log
-
-// S3Logger is a logger compatible with the S3 package
-type S3Logger struct{}
-
-// Log logs a debug message
-func (l *S3Logger) Log(args ...interface{}) {
-	Debugln(args...)
-}
diff --git a/s3/s3.go b/s3/s3.go
index 0afba270e..8c3360729 100644
--- a/s3/s3.go
+++ b/s3/s3.go
@@ -8,8 +8,6 @@ import (
 	"github.com/aws/aws-sdk-go/aws"
 	"github.com/aws/aws-sdk-go/aws/session"
 	"github.com/aws/aws-sdk-go/service/s3/s3manager"
-
-	"github.com/simplesurance/baur/log"
 )
 
 // Client is a S3 uploader client
@@ -18,6 +16,13 @@ type Client struct {
 	uploader *s3manager.Uploader
 }
 
+// Logger defines the interface for an S3 logger
+type Logger interface {
+	Debugf(format string, v ...interface{})
+	Debugln(v ...interface{})
+	DebugEnabled() bool
+}
+
 // DefaultRetries is the number of retries for a S3 upload until an error is
 // raised
 const DefaultRetries = 3
@@ -25,16 +30,20 @@ const DefaultRetries = 3
 // NewClient returns a new S3 Client, configuration is read from env variables
 // or configuration files,
 // see https://docs.aws.amazon.com/sdk-for-go/v1/developer-guide/configuring-sdk.html
-func NewClient() (*Client, error) {
+func NewClient(logger Logger) (*Client, error) {
+	loglvl := aws.LogLevel(aws.LogOff)
+	if logger.DebugEnabled() {
+		loglvl = aws.LogLevel(aws.LogDebug)
+	}
+
 	cfg := aws.Config{
-		Logger:           &log.S3Logger{},
-		LogLevel:         aws.LogLevel(aws.LogDebug),
+		Logger:           aws.LoggerFunc(logger.Debugln),
+		LogLevel:         loglvl,
 		MaxRetries:       aws.Int(DefaultRetries),
 		S3ForcePathStyle: aws.Bool(true),
 	}
 
 	sess, err := session.NewSession(&cfg)
-
 	if err != nil {
 		return nil, err
 	}
@@ -84,7 +93,6 @@ func (c *Client) Upload(file string, dest string) (string, error) {
 	if err != nil {
 		return "", err
 	}
-
 	defer f.Close()
 
 	res, err := c.uploader.Upload(&s3manager.UploadInput{
@@ -92,7 +100,6 @@ func (c *Client) Upload(file string, dest string) (string, error) {
 		Key:    aws.String(fileFromURL(url)),
 		Body:   f,
 	})
-
 	if err != nil {
 		return "", err
 	}
diff --git a/upload/seq/manager.go b/upload/seq/manager.go
index eec81eb71..35c60b091 100644
--- a/upload/seq/manager.go
+++ b/upload/seq/manager.go
@@ -10,10 +10,14 @@ import (
 
 	"github.com/pkg/errors"
 
-	"github.com/simplesurance/baur/log"
 	"github.com/simplesurance/baur/upload"
 )
 
+// Logger defines the logger interface
+type Logger interface {
+	Debugf(format string, v ...interface{})
+}
+
 // Uploader is a sequential uploader
 type Uploader struct {
 	s3             upload.S3Uploader
@@ -22,12 +26,14 @@ type Uploader struct {
 	queue          []upload.Job
 	stopProcessing bool
 	statusChan     chan<- *upload.Result
+	logger         Logger
 }
 
 // New initializes a sequential uploader
 // Status chan must have a buffer count > 1 otherwise a deadlock occurs
-func New(s3Uploader upload.S3Uploader, dockerUploader upload.DockerUploader, status chan<- *upload.Result) *Uploader {
+func New(logger Logger, s3Uploader upload.S3Uploader, dockerUploader upload.DockerUploader, status chan<- *upload.Result) *Uploader {
 	return &Uploader{
+		logger:     logger,
 		s3:         s3Uploader,
 		statusChan: status,
 		lock:       sync.Mutex{},
@@ -62,7 +68,7 @@ func (u *Uploader) Start() {
 			var url string
 			startTs := time.Now()
 
-			log.Debugf("uploading %s\n", job)
+			u.logger.Debugf("uploading %s", job)
 			if job.Type() == upload.JobS3 {
 				url, err = u.s3.Upload(job.LocalPath(), job.RemoteDest())
 				if err != nil {