diff --git a/hc256.cpp b/hc256.cpp
index 5a1750ca..1cdc0cb2 100644
--- a/hc256.cpp
+++ b/hc256.cpp
@@ -96,7 +96,7 @@ void HC256Policy::OperateKeystream(KeystreamOperation operation, byte *output, c
 {
 	size_t msglen = GetBytesPerIteration() * iterationCount;
 	byte* out = output;
-	for (unsigned int i = 0; i < (msglen >> 2); i++, out += 4)
+	for (size_t i = 0; i < (msglen >> 2); i++, out += 4)
 		PutWord(false, LITTLE_ENDIAN_ORDER, out, Generate());
 
 	// If AdditiveCipherTemplate does not have an accumulated keystream
diff --git a/rabbit.cpp b/rabbit.cpp
index a2bf1cbc..f2189b45 100644
--- a/rabbit.cpp
+++ b/rabbit.cpp
@@ -124,7 +124,7 @@ void RabbitPolicy::CipherSetKey(const NameValuePairs &params, const byte *userKe
 void RabbitPolicy::OperateKeystream(KeystreamOperation operation, byte *output, const byte *input, size_t iterationCount)
 {
 	byte* out = output;
-	for (unsigned int i = 0; i<iterationCount; ++i, out += 16)
+	for (size_t i = 0; i<iterationCount; ++i, out += 16)
 	{
 		/* Iterate the system */
 		m_wcy = NextState(m_wc, m_wx, m_wcy);