diff --git a/CMakeLists.txt b/CMakeLists.txt
index 606b5bc1..b30926a0 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -58,6 +58,17 @@ set_property(GLOBAL PROPERTY USE_FOLDERS ON)
 set(CMAKE_CXX_STANDARD 20)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
 
+# A newer MSVC (windows-latest) emits C4875 ("a non-string literal argument to [[gsl::suppress]] is
+# deprecated") from the vendored GSL headers, which several targets compile with warnings-as-error.
+# Suppress this dependency-side deprecation so the Windows build isn't broken by toolchain drift. Must
+# be set before arcana.cpp / Core / Polyfills are added below so they inherit it. Scoped to C++ (the
+# warning only fires for GSL's C++ [[gsl::suppress]] attribute); kept directory-wide because GSL is
+# pulled in transitively by many targets (arcana, AppRuntime, the polyfills) and no first-party code
+# uses a non-string [[gsl::suppress]], so this doesn't mask our own warnings.
+if(MSVC)
+    add_compile_options($<$<COMPILE_LANGUAGE:CXX>:/wd4875>)
+endif()
+
 # --------------------------------------------------
 # Options
 # --------------------------------------------------
diff --git a/Core/Node-API-JSI/CMakeLists.txt b/Core/Node-API-JSI/CMakeLists.txt
index e8e79a96..cb851d62 100644
--- a/Core/Node-API-JSI/CMakeLists.txt
+++ b/Core/Node-API-JSI/CMakeLists.txt
@@ -57,7 +57,13 @@ if(NOT TARGET jsi)
 endif()
 
 target_include_directories(napi
-    PUBLIC "include")
+    PUBLIC
+        "include"
+        # napi.h pulls in the shared <napi/js_native_api_types.h>, which lives in
+        # Core/Node-API/Include/Shared. That sibling isn't built when the engine is JSI
+        # (Core/CMakeLists.txt selects Node-API-JSI instead of Node-API), so reference the shared
+        # headers directly here -- otherwise the JSI napi fails to compile with C1083.
+        "${CMAKE_CURRENT_SOURCE_DIR}/../Node-API/Include/Shared")
 
 target_link_libraries(napi
     PUBLIC jsi)