diff --git a/src/core/core.cpp b/src/core/core.cpp
index f444f5045..b01a61d57 100644
--- a/src/core/core.cpp
+++ b/src/core/core.cpp
@@ -27,7 +27,6 @@
 #include <psapi.h>
 #include <windows.h>
 
-
 #undef GetCurrentTime
 #undef ERROR
 #undef GetMessage
diff --git a/src/core/file_sys/registered_cache.cpp b/src/core/file_sys/registered_cache.cpp
index 7c5ab8b24..3adf620d6 100644
--- a/src/core/file_sys/registered_cache.cpp
+++ b/src/core/file_sys/registered_cache.cpp
@@ -1209,8 +1209,9 @@ void ExternalContentProvider::ProcessNSP(const VirtualFile& file) {
 
                 if (!content_file) {
                     std::string nca_id_lower = nca_id_str;
-                    std::transform(nca_id_lower.begin(), nca_id_lower.end(), nca_id_lower.begin(),
-                                   ::tolower);
+                    std::transform(
+                        nca_id_lower.begin(), nca_id_lower.end(), nca_id_lower.begin(),
+                        [](unsigned char c) { return static_cast<char>(std::tolower(c)); });
                     content_file = nsp.GetFile(fmt::format("{}.nca", nca_id_lower));
                     if (!content_file)
                         content_file = nsp.GetFile(nca_id_lower);
@@ -1239,8 +1240,9 @@ void ExternalContentProvider::ProcessNSP(const VirtualFile& file) {
 
                 if (!content_file) {
                     std::string nca_id_lower = nca_id_str;
-                    std::transform(nca_id_lower.begin(), nca_id_lower.end(), nca_id_lower.begin(),
-                                   ::tolower);
+                    std::transform(
+                        nca_id_lower.begin(), nca_id_lower.end(), nca_id_lower.begin(),
+                        [](unsigned char c) { return static_cast<char>(std::tolower(c)); });
                     content_file = nsp.GetFile(fmt::format("{}.nca", nca_id_lower));
                     if (!content_file)
                         content_file = nsp.GetFile(nca_id_lower);