diff --git a/CMakeLists.txt b/CMakeLists.txt
index caf740a55a..89eb58de39 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -242,6 +242,9 @@ else ()
     ADD_CHECK_CXX_COMPILER_FLAG(CMAKE_CXX_FLAGS CXX_WARN_RANGE_LOOP_ANALYSIS -Wrange-loop-analysis)
     ADD_CHECK_CXX_COMPILER_FLAG(CMAKE_CXX_FLAGS CXX_WARN_TAUTOLOGICAL_ZERO_COMPARE -Wtautological-unsigned-zero-compare)
     ADD_CHECK_CXX_COMPILER_FLAG(CMAKE_CXX_FLAGS CXX_WARN_OLD_STYLE_CAST -Wold-style-cast)
+    # unused-const-variable=1 only checks main compilation unit
+    # unused-const-variable[=2] would check for unused values from headers as well
+    ADD_CHECK_CXX_COMPILER_FLAG(CMAKE_CXX_FLAGS CXX_WARN_UNUSED_CONST_VARIABLE -Wunused-const-variable=1)
     ADD_CHECK_CXX_COMPILER_FLAG(CMAKE_CXX_FLAGS CXX_WNO_CLOBBERED -Wno-clobbered)
     # Disabled due to problems compiling OpenSSL on macOS.
     # ADD_CHECK_CXX_COMPILER_FLAG(CMAKE_CXX_FLAGS CXX_WARN_DOCUMENTATION -Wdocumentation)
diff --git a/src/openrct2/platform/Platform.Win32.cpp b/src/openrct2/platform/Platform.Win32.cpp
index a2e0e82e0f..08e029887e 100644
--- a/src/openrct2/platform/Platform.Win32.cpp
+++ b/src/openrct2/platform/Platform.Win32.cpp
@@ -42,7 +42,9 @@
 #        define swprintf_s(a, b, c, d, ...) swprintf(a, b, c, ##__VA_ARGS__)
 #    endif
 
+#    if _WIN32_WINNT >= 0x0600
 constexpr wchar_t SOFTWARE_CLASSES[] = L"Software\\Classes";
+#    endif
 
 namespace Platform
 {