diff --git a/prometheus/process_collector.go b/prometheus/process_collector.go
index 32ac74a..b80adc6 100644
--- a/prometheus/process_collector.go
+++ b/prometheus/process_collector.go
@@ -16,7 +16,6 @@ package prometheus
 import "github.com/prometheus/procfs"
 
 type processCollector struct {
-	pid             int
 	collectFn       func(chan<- Metric)
 	pidFn           func() (int, error)
 	cpuTotal        *Desc