diff --git a/metric/prometheus.go b/metric/prometheus.go
index 9663db3..6288c67 100644
--- a/metric/prometheus.go
+++ b/metric/prometheus.go
@@ -112,8 +112,10 @@ func (pe *prometheusExporter) loop(ctx context.Context) {
 			return
 
 		case req := <-pe.writerChan:
-			if m := collector.metrics[req.key]; m != nil {
-				atomic.StoreUint64(m.valptr, math.Float64bits(req.val))
+			if collector != nil {
+				if m := collector.metrics[req.key]; m != nil {
+					atomic.StoreUint64(m.valptr, math.Float64bits(req.val))
+				}
 			}
 
 		case nm := <-pe.registerChan: