diff --git a/collector.go b/collector.go
index 330dab5..9330f2e 100644
--- a/collector.go
+++ b/collector.go
@@ -89,20 +89,21 @@ func NewSmokepingCollector(pingers *[]*probing.Pinger, pingResponseSeconds prome
 		// Init all metrics to 0s.
 		ipAddr := pinger.IPAddr().String()
 		host := pinger.Addr()
-		pingResponseDuplicates.WithLabelValues(ipAddr, host, pinger.Source)
-		pingResponseSeconds.WithLabelValues(ipAddr, host, pinger.Source)
-		pingResponseTTL.WithLabelValues(ipAddr, host, pinger.Source)
-		pingSendErrors.WithLabelValues(ipAddr, host, pinger.Source)
+		source := pinger.Source
+		pingResponseDuplicates.WithLabelValues(ipAddr, host, source)
+		pingResponseSeconds.WithLabelValues(ipAddr, host, source)
+		pingResponseTTL.WithLabelValues(ipAddr, host, source)
+		pingSendErrors.WithLabelValues(ipAddr, host, source)
 
 		// Setup handler functions.
 		pinger.OnRecv = func(pkt *probing.Packet) {
-			pingResponseSeconds.WithLabelValues(pkt.IPAddr.String(), host, pinger.Source).Observe(pkt.Rtt.Seconds())
-			pingResponseTTL.WithLabelValues(pkt.IPAddr.String(), host, pinger.Source).Set(float64(pkt.TTL))
+			pingResponseSeconds.WithLabelValues(pkt.IPAddr.String(), host, source).Observe(pkt.Rtt.Seconds())
+			pingResponseTTL.WithLabelValues(pkt.IPAddr.String(), host, source).Set(float64(pkt.TTL))
 			level.Debug(logger).Log("msg", "Echo reply", "ip_addr", pkt.IPAddr,
 				"bytes_received", pkt.Nbytes, "icmp_seq", pkt.Seq, "time", pkt.Rtt, "ttl", pkt.TTL)
 		}
 		pinger.OnDuplicateRecv = func(pkt *probing.Packet) {
-			pingResponseDuplicates.WithLabelValues(pkt.IPAddr.String(), host, pinger.Source).Inc()
+			pingResponseDuplicates.WithLabelValues(pkt.IPAddr.String(), host, source).Inc()
 			level.Debug(logger).Log("msg", "Echo reply (DUP!)", "ip_addr", pkt.IPAddr,
 				"bytes_received", pkt.Nbytes, "icmp_seq", pkt.Seq, "time", pkt.Rtt, "ttl", pkt.TTL)
 		}
@@ -123,7 +124,7 @@ func NewSmokepingCollector(pingers *[]*probing.Pinger, pingResponseSeconds prome
 			level.Debug(logger).Log("msg", "Error receiving packet", "error", err)
 		}
 		pinger.OnSendError = func(pkt *probing.Packet, err error) {
-			pingSendErrors.WithLabelValues(pkt.IPAddr.String(), host, pinger.Source).Inc()
+			pingSendErrors.WithLabelValues(pkt.IPAddr.String(), host, source).Inc()
 			level.Debug(logger).Log("msg", "Error sending packet", "ip_addr", pkt.IPAddr,
 				"bytes_received", pkt.Nbytes, "icmp_seq", pkt.Seq, "time", pkt.Rtt, "ttl", pkt.TTL, "error", err)
 		}