diff --git a/Dockerfile b/Dockerfile
index b07e198..0b222c1 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,5 +1,5 @@
 # Builder stage to
-FROM golang:1.12 as builder
+FROM golang:1.13 as builder
 
 # Add the project in the image
 ADD . /go/src/github.com/kumina/postfix_exporter
@@ -11,7 +11,7 @@ RUN apt-get update -q && apt-get install -qy \
   libsystemd-dev
 
 # Get dependencies and build the static binary
-RUN go get -d ./...
+RUN go test
 RUN go build -a -tags static_all
 
 # Real image
diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..3d5e663
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,15 @@
+module github.com/kumina/postfix_exporter
+
+go 1.13
+
+require (
+	github.com/alecthomas/kingpin v2.2.6+incompatible
+	github.com/coreos/go-systemd/v22 v22.0.0
+	github.com/fsnotify/fsnotify v1.4.7 // indirect
+	github.com/hpcloud/tail v1.0.0
+	github.com/prometheus/client_golang v1.4.1
+	github.com/prometheus/client_model v0.2.0
+	github.com/stretchr/testify v1.4.0
+	gopkg.in/fsnotify.v1 v1.4.7 // indirect
+	gopkg.in/tomb.v1 v1.0.0-20141024135613-dd632973f1e7 // indirect
+)
diff --git a/postfix_exporter_test.go b/postfix_exporter_test.go
new file mode 100644
index 0000000..064f501
--- /dev/null
+++ b/postfix_exporter_test.go
@@ -0,0 +1,161 @@
+package main
+
+import (
+	"github.com/hpcloud/tail"
+	"github.com/prometheus/client_golang/prometheus"
+	io_prometheus_client "github.com/prometheus/client_model/go"
+	"github.com/stretchr/testify/assert"
+	"testing"
+)
+
+func TestPostfixExporter_CollectFromLogline(t *testing.T) {
+	type fields struct {
+		showqPath                       string
+		journal                         *Journal
+		tailer                          *tail.Tail
+		cleanupProcesses                prometheus.Counter
+		cleanupRejects                  prometheus.Counter
+		cleanupNotAccepted              prometheus.Counter
+		lmtpDelays                      *prometheus.HistogramVec
+		pipeDelays                      *prometheus.HistogramVec
+		qmgrInsertsNrcpt                prometheus.Histogram
+		qmgrInsertsSize                 prometheus.Histogram
+		qmgrRemoves                     prometheus.Counter
+		smtpDelays                      *prometheus.HistogramVec
+		smtpTLSConnects                 *prometheus.CounterVec
+		smtpDeferreds                   prometheus.Counter
+		smtpdConnects                   prometheus.Counter
+		smtpdDisconnects                prometheus.Counter
+		smtpdFCrDNSErrors               prometheus.Counter
+		smtpdLostConnections            *prometheus.CounterVec
+		smtpdProcesses                  *prometheus.CounterVec
+		smtpdRejects                    *prometheus.CounterVec
+		smtpdSASLAuthenticationFailures prometheus.Counter
+		smtpdTLSConnects                *prometheus.CounterVec
+		unsupportedLogEntries           *prometheus.CounterVec
+	}
+	type args struct {
+		line  []string
+		count int
+	}
+	tests := []struct {
+		name   string
+		fields fields
+		args   args
+	}{
+		{
+			name: "Single line",
+			args: args{
+				line: []string{
+					"Feb 11 16:49:24 letterman postfix/qmgr[8204]: AAB4D259B1: removed",
+				},
+				count: 1,
+			},
+		},
+		{
+			name: "Multiple lines",
+			args: args{
+				line: []string{
+					"Feb 11 16:49:24 letterman postfix/qmgr[8204]: AAB4D259B1: removed",
+					"Feb 11 16:49:24 letterman postfix/qmgr[8204]: C2032259E6: removed",
+					"Feb 11 16:49:24 letterman postfix/qmgr[8204]: B83C4257DC: removed",
+					"Feb 11 16:49:24 letterman postfix/qmgr[8204]: 721BE256EA: removed",
+					"Feb 11 16:49:25 letterman postfix/qmgr[8204]: CA94A259EB: removed",
+					"Feb 11 16:49:25 letterman postfix/qmgr[8204]: AC1E3259E1: removed",
+					"Feb 11 16:49:25 letterman postfix/qmgr[8204]: D114D221E3: removed",
+					"Feb 11 16:49:25 letterman postfix/qmgr[8204]: A55F82104D: removed",
+					"Feb 11 16:49:25 letterman postfix/qmgr[8204]: D6DAA259BC: removed",
+					"Feb 11 16:49:25 letterman postfix/qmgr[8204]: E3908259F0: removed",
+					"Feb 11 16:49:25 letterman postfix/qmgr[8204]: 0CBB8259BF: removed",
+					"Feb 11 16:49:25 letterman postfix/qmgr[8204]: EA3AD259F2: removed",
+					"Feb 11 16:49:25 letterman postfix/qmgr[8204]: DDEF824B48: removed",
+					"Feb 11 16:49:26 letterman postfix/qmgr[8204]: 289AF21DB9: removed",
+					"Feb 11 16:49:26 letterman postfix/qmgr[8204]: 6192B260E8: removed",
+					"Feb 11 16:49:26 letterman postfix/qmgr[8204]: F2831259F4: removed",
+					"Feb 11 16:49:26 letterman postfix/qmgr[8204]: 09D60259F8: removed",
+					"Feb 11 16:49:26 letterman postfix/qmgr[8204]: 13A19259FA: removed",
+					"Feb 11 16:49:26 letterman postfix/qmgr[8204]: 2D42722065: removed",
+					"Feb 11 16:49:26 letterman postfix/qmgr[8204]: 746E325A0E: removed",
+					"Feb 11 16:49:26 letterman postfix/qmgr[8204]: 4D2F125A02: removed",
+					"Feb 11 16:49:26 letterman postfix/qmgr[8204]: E30BC259EF: removed",
+					"Feb 11 16:49:26 letterman postfix/qmgr[8204]: DC88924DA1: removed",
+					"Feb 11 16:49:26 letterman postfix/qmgr[8204]: 2164B259FD: removed",
+					"Feb 11 16:49:26 letterman postfix/qmgr[8204]: 8C30525A14: removed",
+					"Feb 11 16:49:26 letterman postfix/qmgr[8204]: 8DCCE25A15: removed",
+					"Feb 11 16:49:26 letterman postfix/qmgr[8204]: C5217255D5: removed",
+					"Feb 11 16:49:27 letterman postfix/qmgr[8204]: D8EE625A28: removed",
+					"Feb 11 16:49:27 letterman postfix/qmgr[8204]: 9AD7C25A19: removed",
+					"Feb 11 16:49:27 letterman postfix/qmgr[8204]: D0EEE2596C: removed",
+					"Feb 11 16:49:27 letterman postfix/qmgr[8204]: DFE732172E: removed",
+				},
+				count: 31,
+			},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			e := &PostfixExporter{
+				showqPath:                       tt.fields.showqPath,
+				journal:                         tt.fields.journal,
+				tailer:                          tt.fields.tailer,
+				cleanupProcesses:                tt.fields.cleanupProcesses,
+				cleanupRejects:                  tt.fields.cleanupRejects,
+				cleanupNotAccepted:              tt.fields.cleanupNotAccepted,
+				lmtpDelays:                      tt.fields.lmtpDelays,
+				pipeDelays:                      tt.fields.pipeDelays,
+				qmgrInsertsNrcpt:                tt.fields.qmgrInsertsNrcpt,
+				qmgrInsertsSize:                 tt.fields.qmgrInsertsSize,
+				qmgrRemoves:                     tt.fields.qmgrRemoves,
+				smtpDelays:                      tt.fields.smtpDelays,
+				smtpTLSConnects:                 tt.fields.smtpTLSConnects,
+				smtpDeferreds:                   tt.fields.smtpDeferreds,
+				smtpdConnects:                   tt.fields.smtpdConnects,
+				smtpdDisconnects:                tt.fields.smtpdDisconnects,
+				smtpdFCrDNSErrors:               tt.fields.smtpdFCrDNSErrors,
+				smtpdLostConnections:            tt.fields.smtpdLostConnections,
+				smtpdProcesses:                  tt.fields.smtpdProcesses,
+				smtpdRejects:                    tt.fields.smtpdRejects,
+				smtpdSASLAuthenticationFailures: tt.fields.smtpdSASLAuthenticationFailures,
+				smtpdTLSConnects:                tt.fields.smtpdTLSConnects,
+				unsupportedLogEntries:           tt.fields.unsupportedLogEntries,
+			}
+			counter := testCounter{}
+			e.qmgrRemoves = &counter
+			for _, line := range tt.args.line {
+				e.CollectFromLogline(line)
+			}
+			assert.Equal(t, tt.args.count, counter.Count(), "Wrong number of lines counted")
+			if counter.Count() != tt.args.count {
+				t.Fatal("Counter wrong: ")
+			}
+		})
+	}
+}
+
+type testCounter struct {
+	count int
+}
+
+func (t *testCounter) setCount(count int) {
+	t.count = count
+}
+
+func (t *testCounter) Count() int {
+	return t.count
+}
+
+func (t *testCounter) Add(add float64) {
+}
+func (t *testCounter) Collect(c chan<- prometheus.Metric) {
+}
+func (t *testCounter) Describe(c chan<- *prometheus.Desc) {
+}
+func (t *testCounter) Desc() *prometheus.Desc {
+	return nil
+}
+func (t *testCounter) Inc() {
+	t.count++
+}
+func (t *testCounter) Write(x *io_prometheus_client.Metric) error {
+	return nil
+}
diff --git a/systemd.go b/systemd.go
index b507925..232cae6 100644
--- a/systemd.go
+++ b/systemd.go
@@ -9,7 +9,7 @@ import (
 	"time"
 
 	"github.com/alecthomas/kingpin"
-	"github.com/coreos/go-systemd/sdjournal"
+	"github.com/coreos/go-systemd/v22/sdjournal"
 )
 
 // Journal represents a lockable systemd journal.