diff --git a/source/lib/sysdep/os/win/wposix/wposix.cpp b/source/lib/sysdep/os/win/wposix/wposix.cpp
index ce0eb2daf8..efa067cb6a 100644
--- a/source/lib/sysdep/os/win/wposix/wposix.cpp
+++ b/source/lib/sysdep/os/win/wposix/wposix.cpp
@@ -1,4 +1,4 @@
-/* Copyright (C) 2010 Wildfire Games.
+/* Copyright (C) 2026 Wildfire Games.
  *
  * Permission is hereby granted, free of charge, to any person obtaining
  * a copy of this software and associated documentation files (the
@@ -25,21 +25,25 @@
  */
 
 #include "precompiled.h"
-#include "lib/sysdep/os/win/wposix/wposix.h"
 
-#include "lib/sysdep/os/win/wposix/wposix_internal.h"
-#include "lib/bits.h"
+#include "wposix.h"
+
+#include "lib/sysdep/os/win/win.h"
+
+#include <cerrno>
+#include <cstdlib>
+#include <cstring>
 
 
 int setenv(const char* envname, const char* envval, int overwrite)
 {
-	if(!envname || envname[0] == '\0' || strchr(envname, '='))
+	if(!envname || envname[0] == '\0' || std::strchr(envname, '='))
 	{
 		errno = EINVAL;
 		return -1;
 	}
 
-	if(overwrite || !getenv(envname))
+	if(overwrite || !std::getenv(envname))
 		SetEnvironmentVariableA(envname, envval);
 
 	return 0;
diff --git a/source/lib/sysdep/os/win/wposix/wposix.h b/source/lib/sysdep/os/win/wposix/wposix.h
index a21e87bff7..cbc64c7558 100644
--- a/source/lib/sysdep/os/win/wposix/wposix.h
+++ b/source/lib/sysdep/os/win/wposix/wposix.h
@@ -54,17 +54,4 @@
 
 int setenv(const char* envname, const char* envval, int overwrite);
 
-
-//
-// <math.h>
-//
-
-// (missing on MSVC)
-#ifndef INFINITY
-#define INFINITY					(std::numeric_limits<float>::infinity())
-#endif
-#ifndef NAN
-#define NAN							(std::numeric_limits<float>::quiet_NaN())
-#endif
-
 #endif	// #ifndef INCLUDED_WPOSIX
diff --git a/source/scriptinterface/tests/test_ScriptConversions.h b/source/scriptinterface/tests/test_ScriptConversions.h
index 482ae99f56..7dea78522c 100644
--- a/source/scriptinterface/tests/test_ScriptConversions.h
+++ b/source/scriptinterface/tests/test_ScriptConversions.h
@@ -1,4 +1,4 @@
-/* Copyright (C) 2025 Wildfire Games.
+/* Copyright (C) 2026 Wildfire Games.
  * This file is part of 0 A.D.
  *
  * 0 A.D. is free software: you can redistribute it and/or modify
@@ -213,7 +213,7 @@ public:
 
 		float f = 0;
 		JS::RootedValue testNANVal(rq.cx);
-		Script::ToJSVal(rq, &testNANVal, NAN);
+		Script::ToJSVal(rq, &testNANVal, std::numeric_limits<float>::quiet_NaN());
 		TS_ASSERT(Script::FromJSVal(rq, testNANVal, f));
 		TS_ASSERT(std::isnan(f));
 	}