diff --git a/collector/helper.go b/collector/helper.go
index 527fa742..0f72ae94 100644
--- a/collector/helper.go
+++ b/collector/helper.go
@@ -48,7 +48,7 @@ func bytesToString(byteArray []byte) string {
 
 var metricNameRegex = regexp.MustCompile(`_*[^0-9A-Za-z_]+_*`)
 
-// Sanitize the given metric name by replacing invalid characters by underscores.
+// SanitizeMetricName sanitize the given metric name by replacing invalid characters by underscores.
 //
 // OpenMetrics and the Prometheus exposition format require the metric name
 // to consist only of alphanumericals and "_", ":" and they must not start
diff --git a/collector/lnstat_linux.go b/collector/lnstat_linux.go
index bf67cfa5..b3c90dc0 100644
--- a/collector/lnstat_linux.go
+++ b/collector/lnstat_linux.go
@@ -49,7 +49,7 @@ func (c *lnstatCollector) Update(ch chan<- prometheus.Metric) error {
 
 	netStats, err := fs.NetStat()
 	if err != nil {
-		return fmt.Errorf("Lnstat error: %s", err)
+		return fmt.Errorf("lnstat error: %s", err)
 	}
 
 	for _, netStatFile := range netStats {
diff --git a/collector/perf_linux.go b/collector/perf_linux.go
index 2e1e0b3f..7f239ed6 100644
--- a/collector/perf_linux.go
+++ b/collector/perf_linux.go
@@ -50,7 +50,7 @@ func perfTracepointFlagToTracepoints(tracepointsFlag []string) ([]*perfTracepoin
 	for i, tracepoint := range tracepointsFlag {
 		split := strings.Split(tracepoint, ":")
 		if len(split) != 2 {
-			return nil, fmt.Errorf("Invalid tracepoint config %v", tracepoint)
+			return nil, fmt.Errorf("invalid tracepoint config %v", tracepoint)
 		}
 		tracepoints[i] = &perfTracepoint{
 			subsystem: split[0],
@@ -598,9 +598,6 @@ func (c *perfCollector) updateHardwareStats(ch chan<- prometheus.Metric) error {
 		if err := (*profiler).Profile(hwProfile); err != nil {
 			return err
 		}
-		if hwProfile == nil {
-			continue
-		}
 
 		cpuid := strconv.Itoa(c.hwProfilerCPUMap[profiler])
 
@@ -670,9 +667,6 @@ func (c *perfCollector) updateSoftwareStats(ch chan<- prometheus.Metric) error {
 		if err := (*profiler).Profile(swProfile); err != nil {
 			return err
 		}
-		if swProfile == nil {
-			continue
-		}
 
 		cpuid := strconv.Itoa(c.swProfilerCPUMap[profiler])
 
@@ -726,9 +720,6 @@ func (c *perfCollector) updateCacheStats(ch chan<- prometheus.Metric) error {
 		if err := (*profiler).Profile(cacheProfile); err != nil {
 			return err
 		}
-		if cacheProfile == nil {
-			continue
-		}
 
 		cpuid := strconv.Itoa(c.cacheProfilerCPUMap[profiler])
 
diff --git a/collector/systemd_linux.go b/collector/systemd_linux.go
index 453ebde4..ae5547f7 100644
--- a/collector/systemd_linux.go
+++ b/collector/systemd_linux.go
@@ -74,7 +74,6 @@ type systemdCollector struct {
 	socketCurrentConnectionsDesc  *prometheus.Desc
 	socketRefusedConnectionsDesc  *prometheus.Desc
 	systemdVersionDesc            *prometheus.Desc
-	systemdVersion                float64
 	unitIncludePattern            *regexp.Regexp
 	unitExcludePattern            *regexp.Regexp
 	logger                        log.Logger
diff --git a/collector/systemd_linux_test.go b/collector/systemd_linux_test.go
index 1b55af7c..7e9fd1b2 100644
--- a/collector/systemd_linux_test.go
+++ b/collector/systemd_linux_test.go
@@ -14,11 +14,11 @@
 package collector
 
 import (
-	"github.com/go-kit/log"
 	"regexp"
 	"testing"
 
 	"github.com/coreos/go-systemd/dbus"
+	"github.com/go-kit/log"
 )
 
 // Creates mock UnitLists