diff --git a/whisper/whisperv5/doc.go b/whisper/whisperv5/doc.go
index c37bcb9263..223d8246ee 100644
--- a/whisper/whisperv5/doc.go
+++ b/whisper/whisperv5/doc.go
@@ -51,10 +51,11 @@ const (
 	paddingMask   = byte(3)
 	signatureFlag = byte(4)
 
-	TopicLength     = 4
-	signatureLength = 65
-	aesKeyLength    = 32
-	saltLength      = 12
+	TopicLength       = 4
+	signatureLength   = 65
+	aesKeyLength      = 32
+	saltLength        = 12
+	AESNonceMaxLength = 12
 
 	MaxMessageLength = 0xFFFF // todo: remove this restriction after testing in morden and analizing stats. this should be regulated by MinimumPoW.
 	MinimumPoW       = 10.0   // todo: review
diff --git a/whisper/whisperv5/envelope.go b/whisper/whisperv5/envelope.go
index cb8fc89d19..6835e22c03 100644
--- a/whisper/whisperv5/envelope.go
+++ b/whisper/whisperv5/envelope.go
@@ -131,7 +131,7 @@ func (e *Envelope) calculatePoW(diff uint32) {
 	h = crypto.Keccak256(buf)
 	firstBit := common.FirstBitSet(common.BigD(h))
 	x := math.Pow(2, float64(firstBit))
-	x /= float64(len(e.Data) + len(e.Salt) + len(e.AESNonce))
+	x /= float64(len(e.Data)) // we only count e.Data, other variable-sized members are checked in Whisper.add()
 	x /= float64(e.TTL + diff)
 	e.pow = x
 }
diff --git a/whisper/whisperv5/whisper.go b/whisper/whisperv5/whisper.go
index 3402c7bf66..8a9770fdd0 100644
--- a/whisper/whisperv5/whisper.go
+++ b/whisper/whisperv5/whisper.go
@@ -419,7 +419,7 @@ func (wh *Whisper) add(envelope *Envelope) error {
 		return fmt.Errorf("oversized Version")
 	}
 
-	if len(envelope.AESNonce) > 12 {
+	if len(envelope.AESNonce) > AESNonceMaxLength {
 		// the standard AES GSM nonce size is 12,
 		// but const gcmStandardNonceSize cannot be accessed directly
 		return fmt.Errorf("oversized AESNonce")