diff --git a/windows/svc/service.go b/windows/svc/service.go
index 51b94dff..ee3d6965 100644
--- a/windows/svc/service.go
+++ b/windows/svc/service.go
@@ -72,7 +72,7 @@ type Status struct {
 	Accepts    Accepted
 	CheckPoint uint32 // used to report progress during a lengthy operation
 	WaitHint   uint32 // estimated time required for a pending operation, in milliseconds
-	ProcessId  uint32
+	ProcessId  uint32 // if the service is running, the process identifier of it, and otherwise zero
 }
 
 // ChangeRequest is sent to the service Handler to request service status change.