diff --git a/lib/src/ecpair.dart b/lib/src/ecpair.dart
index 4ba3559..f19dd9e 100644
--- a/lib/src/ecpair.dart
+++ b/lib/src/ecpair.dart
@@ -93,7 +93,7 @@ class ECPair {
   }
 }
 
-const int _SIZE_BYTE = 255;
+const int _SIZE_BYTE = 256;
 
 Uint8List _randomBytes(int size) {
   final rng = Random.secure();