diff --git a/source/crypto/chacha b/source/crypto/chacha
index 4a09e13..4201f08 100644
--- a/source/crypto/chacha
+++ b/source/crypto/chacha
@@ -231,7 +231,7 @@ namespace gtl {
                 const block_type block = chacha::transform_block(key, initialisation_vector);
                 result = chacha::xor_data(block, data);;
                 ++counter;
-                for (int i = 0; i < 4; ++i) {
+                for (unsigned int i = 0; i < 4; ++i) {
                     initialisation_vector.data[i] = unpack_byte(counter, i);
                 }
             }
@@ -240,7 +240,7 @@ namespace gtl {
                 const block_type block = chacha::transform_block(key, initialisation_vector);
                 result = chacha::xor_data(block, data);;
                 ++counter;
-                for (int i = 0; i < 8; ++i) {
+                for (unsigned int i = 0; i < 8; ++i) {
                     initialisation_vector.data[i] = unpack_byte(counter, i);
                 }
             }
diff --git a/source/game/mastermind b/source/game/mastermind
index 6d843ee..8b83497 100644
--- a/source/game/mastermind
+++ b/source/game/mastermind
@@ -138,7 +138,7 @@ namespace gtl {
                 }
                 // Select the minimum of the maximums to get the best guess.
                 std::vector<unsigned int>::iterator min_element = std::min_element(scores.begin(), scores.end());
-                guess = unguessed_codes[std::distance(scores.begin(), min_element)];
+                guess = unguessed_codes[static_cast<unsigned int>(std::distance(scores.begin(), min_element))];
                 // Check to see if there is a possible code with the same score, if so, prefer that.
                 const unsigned int min_score = *min_element;
                 for (unsigned int i = 0; i < unguessed_codes.size(); ++i) {