diff --git a/aggregator/aggregator.go b/aggregator/aggregator.go
index a2a092a8..7a345337 100644
--- a/aggregator/aggregator.go
+++ b/aggregator/aggregator.go
@@ -160,6 +160,7 @@ func (a *Aggregator) Flush(ts uint) {
 		if agg.ts < ts {
 			result := a.fn(agg.values)
 			metric := fmt.Sprintf("%s %f %d", string(agg.key), result, agg.ts)
+			log.Debug("aggregator emitting %q", metric)
 			a.out <- []byte(metric)
 		} else {
 			aggregations2 = append(aggregations2, agg)
diff --git a/aggregator/init.go b/aggregator/init.go
new file mode 100644
index 00000000..05c23f78
--- /dev/null
+++ b/aggregator/init.go
@@ -0,0 +1,9 @@
+package aggregator
+
+import logging "github.com/op/go-logging"
+
+var log = logging.MustGetLogger("aggregator") // for tests. overridden by main
+
+func SetLogger(l *logging.Logger) {
+	log = l
+}
diff --git a/cmd/carbon-relay-ng/carbon-relay-ng.go b/cmd/carbon-relay-ng/carbon-relay-ng.go
index ea7445eb..b6a81344 100644
--- a/cmd/carbon-relay-ng/carbon-relay-ng.go
+++ b/cmd/carbon-relay-ng/carbon-relay-ng.go
@@ -14,6 +14,7 @@ import (
 
 	"github.com/BurntSushi/toml"
 	"github.com/Dieterbe/go-metrics"
+	"github.com/graphite-ng/carbon-relay-ng/aggregator"
 	"github.com/graphite-ng/carbon-relay-ng/badmetrics"
 	"github.com/graphite-ng/carbon-relay-ng/cfg"
 	"github.com/graphite-ng/carbon-relay-ng/destination"
@@ -57,6 +58,7 @@ func init() {
 	destination.SetLogger(log)
 	telnet.SetLogger(log)
 	web.SetLogger(log)
+	aggregator.SetLogger(log)
 }
 
 func usage() {