diff --git a/src/CryptoBase/Macs/Poly1305/Poly1305X86.cs b/src/CryptoBase/Macs/Poly1305/Poly1305X86.cs
index 82ada0a0..427ca6c0 100644
--- a/src/CryptoBase/Macs/Poly1305/Poly1305X86.cs
+++ b/src/CryptoBase/Macs/Poly1305/Poly1305X86.cs
@@ -139,7 +139,7 @@ private void MultiplyR(ref uint a0, ref uint a1, ref uint a2, ref uint a3, ref u
 	/// d = h * r
 	/// </summary>
 	private void MultiplyR(
-		ref Vector128<uint> h01, ref Vector128<uint> h23, ref Vector128<uint> h44,
+		ref readonly Vector128<uint> h01, ref readonly Vector128<uint> h23, ref readonly Vector128<uint> h44,
 		out ulong d0, out ulong d1, out ulong d2, out ulong d3, out ulong d4)
 	{
 		// h0 * r0 + h2 * s3
diff --git a/src/CryptoBase/SymmetricCryptos/StreamCryptos/ChaCha20Utils.cs b/src/CryptoBase/SymmetricCryptos/StreamCryptos/ChaCha20Utils.cs
index 071b66f2..f84d56a9 100644
--- a/src/CryptoBase/SymmetricCryptos/StreamCryptos/ChaCha20Utils.cs
+++ b/src/CryptoBase/SymmetricCryptos/StreamCryptos/ChaCha20Utils.cs
@@ -59,7 +59,7 @@ private static void QuarterRound(ref uint a, ref uint b, ref uint c, ref uint d)
 	}
 
 	[MethodImpl(MethodImplOptions.AggressiveInlining)]
-	private static void Step(ref uint a, ref uint b, ref uint c, byte i)
+	private static void Step(ref uint a, ref readonly uint b, ref uint c, byte i)
 	{
 		a += b;
 		c = (a ^ c).RotateLeft(i);