diff --git a/Source/Contents/MapSkyMgr.cpp b/Source/Contents/MapSkyMgr.cpp
index 9df6a06b..2d168c78 100644
--- a/Source/Contents/MapSkyMgr.cpp
+++ b/Source/Contents/MapSkyMgr.cpp
@@ -11,6 +11,7 @@
 #include "Resource/World/TerrainResource.h"
 #include "Utility/Math/AffineMatrix.h"
 
+#include <cctype>
 #include <cstdlib>
 #include <new>
 
@@ -41,6 +42,11 @@ CWeatherEffect g_weatherEffect;
 // GLOBAL: gl_24633
 float g_depthAverageHalf = 0.5f;
 
+// GLOBAL: gl_25254
+std::vector<std::string> g_registeredLowercaseNames;
+
+static_assert(sizeof(std::vector<std::string>) == 12);
+
 // OFFSET: 0x005B8D50
 // FUNCTION: fn_03431
 CMapSkyMgr::CMapSkyMgr() : m_script(nullptr) {
@@ -469,3 +475,24 @@ CMapSkyMgr* GetMapSkyMgr() {
 // FUNCTION: fn_24378
 void IgnoreNull() {
 }
+
+// OFFSET: 0x00E5D110
+// FUNCTION: fn_24379
+void RegisterLowercaseName(const char* name) {
+  if (!name) {
+    return;
+  }
+
+  std::string lowered(name);
+  for (char& character : lowered) {
+    character = static_cast<char>(std::tolower(static_cast<unsigned char>(character)));
+  }
+
+  for (const std::string& entry : g_registeredLowercaseNames) {
+    if (entry == lowered) {
+      return;
+    }
+  }
+
+  g_registeredLowercaseNames.push_back(lowered.c_str());
+}