diff --git a/whisper/whisperv5/doc.go b/whisper/whisperv5/doc.go
index 58f2bd9852..d60868f670 100644
--- a/whisper/whisperv5/doc.go
+++ b/whisper/whisperv5/doc.go
@@ -57,7 +57,7 @@ const (
 	keyIdSize         = 32
 
 	DefaultMaxMessageLength = 1024 * 1024
-	DefaultMinimumPoW       = 2.0 // todo: review after testing.
+	DefaultMinimumPoW       = 1.0 // todo: review after testing.
 
 	padSizeLimitLower = 128 // it can not be less - we don't want to reveal the absence of signature
 	padSizeLimitUpper = 256 // just an arbitrary number, could be changed without losing compatibility
diff --git a/whisper/whisperv5/envelope.go b/whisper/whisperv5/envelope.go
index 5d882d5dc2..94a091b200 100644
--- a/whisper/whisperv5/envelope.go
+++ b/whisper/whisperv5/envelope.go
@@ -95,6 +95,9 @@ func (e *Envelope) Seal(options *MessageParams) error {
 		e.Expiry += options.WorkTime
 	} else {
 		target = e.powToFirstBit(options.PoW)
+		if target < 1 {
+			target = 1
+		}
 	}
 
 	buf := make([]byte, 64)