diff --git a/internal/server/v1/firehose/mappings.go b/internal/server/v1/firehose/mappings.go
index f8fa0b6..10b0f25 100644
--- a/internal/server/v1/firehose/mappings.go
+++ b/internal/server/v1/firehose/mappings.go
@@ -33,7 +33,7 @@ type firehoseLabels struct {
 
 type moduleConfig struct {
 	State    string                  `json:"state"`
-	StopTime *time.Time              `json:"stop_time"`
+	StopTime *time.Time              `json:"stop_time,omitempty"`
 	Telegraf map[string]interface{}  `json:"telegraf"`
 	Firehose moduleConfigFirehoseDef `json:"firehose"`
 }