diff --git a/ConflictSet.cpp b/ConflictSet.cpp
index 076ca89..6f9e210 100644
--- a/ConflictSet.cpp
+++ b/ConflictSet.cpp
@@ -729,7 +729,7 @@ void lastLeqMulti(Arena &arena, Node *root, std::span<Key> keys,
   for (auto iter = extrema(node, false); iter != nullptr;) {
     auto *next = ::next(iter, true);
     std::string key;
-    for (auto c : std::string_view((const char *)(iter + 1), iter->len)) {
+    for (uint8_t c : std::string_view((const char *)(iter + 1), iter->len)) {
       key += "x";
       key += "0123456789abcdef"[c / 16];
       key += "0123456789abcdef"[c % 16];
@@ -1200,7 +1200,7 @@ struct ReferenceImpl {
   void printLogical(std::string &result) {
     for (const auto &[k, v] : writeVersionMap) {
       std::string key;
-      for (auto c : k) {
+      for (uint8_t c : k) {
         key += "x";
         key += "0123456789abcdef"[c / 16];
         key += "0123456789abcdef"[c % 16];