diff --git a/main.go b/main.go
index 23491e0..de3267e 100644
--- a/main.go
+++ b/main.go
@@ -501,7 +501,9 @@ func WriteDatapoint(mytime int64, deveui string, devaddr string, v uint8, h uint
 			vp = 100
 		}
 
-		sv = fmt.Sprintf("v=%di,vp=%di,", int32(v)*7+2510, vp)
+		if v > 0 {
+			sv = fmt.Sprintf("v=%di,vp=%di,", int32(v)*7+2510, vp)
+		}
 
 		s := ""
 		sfw := ""