diff --git a/sphinx.go b/sphinx.go
index ebb74eebc..061d9fc4b 100644
--- a/sphinx.go
+++ b/sphinx.go
@@ -203,10 +203,10 @@ func NewMixHeader(dest LightningAddress, identifier [securityParameter]byte,
 // "filler" bytes produced by this function at the last hop. Using this
 // methodology, the size of the mix header stays constant at each hop.
 func generateHeaderPadding(numHops int, sharedSecrets [][sharedSecretSize]byte) []byte {
-	fillerSize := (2*(numMaxHops-1) + 3) * securityParameter
-	filler := make([]byte, fillerSize)
+	filler := make([]byte, 2*(numHops-1)*securityParameter)
 
 	for i := 1; i < numHops; i++ {
+		totalFillerSize := (2*(numMaxHops-i) + 3) * securityParameter
 		padding := bytes.Repeat([]byte{0}, 2*securityParameter)
 
 		var tempBuf bytes.Buffer
@@ -216,7 +216,7 @@ func generateHeaderPadding(numHops int, sharedSecrets [][sharedSecretSize]byte)
 		streamBytes := generateCipherStream(generateKey("rho", sharedSecrets[i-1]),
 			numStreamBytes)
 
-		xor(filler, tempBuf.Bytes(), streamBytes[fillerSize:])
+		xor(filler, tempBuf.Bytes(), streamBytes[totalFillerSize:])
 	}
 
 	return filler