diff --git a/build/premake/premake5.lua b/build/premake/premake5.lua
index b86e00a9d1..a182971c14 100644
--- a/build/premake/premake5.lua
+++ b/build/premake/premake5.lua
@@ -691,6 +691,8 @@ function setup_all_libs ()
 		"sdl",
 		"boost",	-- dragged in via server->simulation.h->random and NetSession.h->lockfree
 		"fmt",
+		"libxml2",
+		"iconv",
 	}
 	if not _OPTIONS["without-miniupnpc"] then
 		table.insert(extern_libs, "miniupnpc")
@@ -780,6 +782,8 @@ function setup_all_libs ()
 		"boost",
 		"spidermonkey",
 		"fmt",
+		"libxml2",
+		"iconv",
 	}
 	setup_static_lib_project("simulation2", source_dirs, extern_libs, {})
 
@@ -861,6 +865,8 @@ function setup_all_libs ()
 		"fmt",
 		"freetype",
 		"icu",
+		"libxml2",
+		"iconv",
 	}
 	if not _OPTIONS["without-nvtt"] then
 		table.insert(extern_libs, "nvtt")
@@ -877,6 +883,8 @@ function setup_all_libs ()
 		"sdl",	-- key definitions
 		"spidermonkey",
 		"fmt",
+		"libxml2",
+		"iconv",
 	}
 	setup_static_lib_project("atlas", source_dirs, extern_libs, {})
 
@@ -898,6 +906,7 @@ function setup_all_libs ()
 		"icu",
 		"iconv",
 		"fmt",
+		"libxml2",
 	}
 	if not _OPTIONS["without-audio"] then
 		table.insert(extern_libs, "openal")
diff --git a/source/lib/posix/posix.h b/source/lib/posix/posix.h
index 9073942223..230c454e71 100644
--- a/source/lib/posix/posix.h
+++ b/source/lib/posix/posix.h
@@ -1,4 +1,4 @@
-/* Copyright (C) 2020 Wildfire Games.
+/* Copyright (C) 2025 Wildfire Games.
  *
  * Permission is hereby granted, free of charge, to any person obtaining
  * a copy of this software and associated documentation files (the
@@ -93,6 +93,8 @@ need only be renamed (e.g. _open, _stat).
 #define strncasecmp _strnicmp
 #define wcscasecmp _wcsicmp
 #define wcsncasecmp _wcsnicmp
+#else
+#include <strings.h> // IWYU pragma: export
 #endif
 
 #if OS_MACOSX
diff --git a/source/ps/XMB/XMBData.cpp b/source/ps/XMB/XMBData.cpp
index 54104b59ef..26b28045f9 100644
--- a/source/ps/XMB/XMBData.cpp
+++ b/source/ps/XMB/XMBData.cpp
@@ -1,4 +1,4 @@
-/* Copyright (C) 2021 Wildfire Games.
+/* Copyright (C) 2025 Wildfire Games.
  * This file is part of 0 A.D.
  *
  * 0 A.D. is free software: you can redistribute it and/or modify
@@ -17,9 +17,16 @@
 
 #include "precompiled.h"
 
-#include "lib/byte_order.h"	// FOURCC_LE
+#include "XMBData.h"
+
+#include "lib/debug.h"
+#include "lib/posix/posix.h"
+#include "lib/secure_crt.h"
+#include "lib/types.h"
 #include "ps/XMB/XMBStorage.h"
-#include "ps/XML/Xeromyces.h"
+
+#include <cstring>
+#include <memory>
 
 template<typename T>
 static inline T read(const void* ptr)
diff --git a/source/ps/XMB/XMBData.h b/source/ps/XMB/XMBData.h
index 06185ecca2..b3467cd18e 100644
--- a/source/ps/XMB/XMBData.h
+++ b/source/ps/XMB/XMBData.h
@@ -1,4 +1,4 @@
-/* Copyright (C) 2021 Wildfire Games.
+/* Copyright (C) 2025 Wildfire Games.
  * This file is part of 0 A.D.
  *
  * 0 A.D. is free software: you can redistribute it and/or modify
@@ -82,15 +82,14 @@ XMB_Text {
 
 #include "ps/CStr.h"
 
-#include <string>
+#include <cstddef>
+#include <iterator>
 #include <string_view>
 
-class XMBStorage;
-
+class XMBAttributeList;
 class XMBElement;
 class XMBElementList;
-class XMBAttributeList;
-
+class XMBStorage;
 
 class XMBData
 {
diff --git a/source/ps/XMB/XMBStorage.cpp b/source/ps/XMB/XMBStorage.cpp
index 57ad686704..35aac7a17d 100644
--- a/source/ps/XMB/XMBStorage.cpp
+++ b/source/ps/XMB/XMBStorage.cpp
@@ -1,4 +1,4 @@
-/* Copyright (C) 2024 Wildfire Games.
+/* Copyright (C) 2025 Wildfire Games.
  * This file is part of 0 A.D.
  *
  * 0 A.D. is free software: you can redistribute it and/or modify
@@ -19,17 +19,30 @@
 
 #include "XMBStorage.h"
 
+#include "lib/debug.h"
 #include "lib/file/io/write_buffer.h"
 #include "lib/file/vfs/vfs.h"
 #include "ps/CLogger.h"
 #include "scriptinterface/Object.h"
 #include "scriptinterface/ScriptConversions.h"
-#include "scriptinterface/ScriptExtraHeaders.h"
 #include "scriptinterface/ScriptInterface.h"
+#include "scriptinterface/ScriptRequest.h"
 
+#include <algorithm>
+#include <iterator>
+#include <js/Array.h>
+#include <js/PropertyAndElement.h>
+#include <js/RootingAPI.h>
+#include <js/Value.h>
+#include <jsapi.h>
+#include <jspubtd.h>
 #include <libxml/parser.h>
+#include <libxml/xmlmemory.h>
+#include <libxml/xmlstring.h>
 #include <string_view>
 #include <unordered_map>
+#include <utility>
+#include <vector>
 
 const char* XMBStorage::HeaderMagicStr = "XMB0";
 const char* XMBStorage::UnfinishedHeaderMagicStr = "XMBu";
diff --git a/source/ps/XMB/XMBStorage.h b/source/ps/XMB/XMBStorage.h
index d5687f21ab..9bb4375624 100644
--- a/source/ps/XMB/XMBStorage.h
+++ b/source/ps/XMB/XMBStorage.h
@@ -1,4 +1,4 @@
-/* Copyright (C) 2021 Wildfire Games.
+/* Copyright (C) 2025 Wildfire Games.
  * This file is part of 0 A.D.
  *
  * 0 A.D. is free software: you can redistribute it and/or modify
@@ -18,9 +18,15 @@
 #ifndef INCLUDED_XMBSTORAGE
 #define INCLUDED_XMBSTORAGE
 
-#include "scriptinterface/ScriptForward.h"
+#include "lib/types.h"
 
+#include <cstddef>
+#include <js/TypeDecls.h>
+#include <libxml/parser.h>
 #include <memory>
+#include <string>
+
+class ScriptInterface;
 
 typedef struct _xmlDoc xmlDoc;
 typedef xmlDoc* xmlDocPtr;
diff --git a/source/ps/XML/RelaxNG.cpp b/source/ps/XML/RelaxNG.cpp
index d8eb5f75a5..6380e95f4d 100644
--- a/source/ps/XML/RelaxNG.cpp
+++ b/source/ps/XML/RelaxNG.cpp
@@ -19,17 +19,24 @@
 
 #include "RelaxNG.h"
 
+#include "lib/code_annotation.h"
 #include "lib/timer.h"
-#include "lib/utf8.h"
+#include "lib/types.h"
 #include "ps/CLogger.h"
 #include "ps/CStr.h"
+#include "ps/Errors.h"
 #include "ps/Filesystem.h"
 
+#include <cstddef>
 #include <libxml/parser.h>
 #include <libxml/relaxng.h>
+#include <libxml/xmlerror.h>
+#include <libxml/xmlversion.h>
 #include <map>
+#include <memory>
 #include <mutex>
 #include <type_traits>
+#include <utility>
 
 TIMER_ADD_CLIENT(xml_validation);
 
diff --git a/source/ps/XML/RelaxNG.h b/source/ps/XML/RelaxNG.h
index 467d2a0ae1..f7edeef13e 100644
--- a/source/ps/XML/RelaxNG.h
+++ b/source/ps/XML/RelaxNG.h
@@ -1,4 +1,4 @@
-/* Copyright (C) 2021 Wildfire Games.
+/* Copyright (C) 2025 Wildfire Games.
  * This file is part of 0 A.D.
  *
  * 0 A.D. is free software: you can redistribute it and/or modify
@@ -19,8 +19,12 @@
 #define INCLUDED_RELAXNG
 
 #include "lib/file/vfs/vfs.h"
+#include "lib/file/vfs/vfs_path.h"
 #include "maths/MD5.h"
 
+#include <libxml/parser.h>
+#include <string>
+
 typedef struct _xmlRelaxNG xmlRelaxNG;
 typedef xmlRelaxNG *xmlRelaxNGPtr;
 typedef struct _xmlDoc xmlDoc;
diff --git a/source/ps/XML/XMLWriter.cpp b/source/ps/XML/XMLWriter.cpp
index b74e7bc88e..e0d687d0d5 100644
--- a/source/ps/XML/XMLWriter.cpp
+++ b/source/ps/XML/XMLWriter.cpp
@@ -1,4 +1,4 @@
-/* Copyright (C) 2021 Wildfire Games.
+/* Copyright (C) 2025 Wildfire Games.
  * This file is part of 0 A.D.
  *
  * 0 A.D. is free software: you can redistribute it and/or modify
@@ -19,14 +19,23 @@
 
 #include "XMLWriter.h"
 
-#include "ps/CLogger.h"
-#include "ps/Filesystem.h"
-#include "ps/XML/Xeromyces.h"
-#include "lib/utf8.h"
+#include "lib/alignment.h"
 #include "lib/allocators/shared_ptr.h"
-#include "lib/sysdep/cpu.h"
+#include "lib/debug.h"
+#include "lib/path.h"
+#include "lib/status.h"
+#include "lib/types.h"
+#include "lib/utf8.h"
 #include "maths/Fixed.h"
+#include "ps/CLogger.h"
+#include "ps/XMB/XMBData.h"
+#include "ps/XMB/XMBStorage.h"
+#include "ps/XML/Xeromyces.h"
 
+#include <cstring>
+#include <memory>
+#include <sstream>
+#include <string>
 
 // TODO (maybe): Write to the file frequently, instead of buffering
 // the entire file, so that large files get written faster.
diff --git a/source/ps/XML/XMLWriter.h b/source/ps/XML/XMLWriter.h
index b7d6e3402d..89db1718a7 100644
--- a/source/ps/XML/XMLWriter.h
+++ b/source/ps/XML/XMLWriter.h
@@ -1,4 +1,4 @@
-/* Copyright (C) 2021 Wildfire Games.
+/* Copyright (C) 2025 Wildfire Games.
  * This file is part of 0 A.D.
  *
  * 0 A.D. is free software: you can redistribute it and/or modify
@@ -62,6 +62,7 @@
  */
 
 #include "lib/file/vfs/vfs.h"
+#include "lib/file/vfs/vfs_path.h"
 #include "ps/CStr.h"
 
 class XMBElement;
diff --git a/source/ps/XML/Xeromyces.cpp b/source/ps/XML/Xeromyces.cpp
index e2e313c2d5..ed4b2e4d41 100644
--- a/source/ps/XML/Xeromyces.cpp
+++ b/source/ps/XML/Xeromyces.cpp
@@ -17,23 +17,29 @@
 
 #include "precompiled.h"
 
-#include <vector>
-#include <set>
-#include <map>
-#include <mutex>
-#include <stack>
-#include <algorithm>
-
-#include "maths/MD5.h"
-#include "ps/CacheLoader.h"
-#include "ps/CLogger.h"
-#include "ps/Filesystem.h"
-
-#include "RelaxNG.h"
 #include "Xeromyces.h"
 
+#include "RelaxNG.h"
+#include "lib/code_annotation.h"
+#include "lib/debug.h"
+#include "lib/file/vfs/vfs.h"
+#include "lib/path.h"
+#include "lib/status.h"
+#include "maths/MD5.h"
+#include "ps/CLogger.h"
+#include "ps/CStr.h"
+#include "ps/CacheLoader.h"
+#include "ps/Filesystem.h"
+
+#include <cstring>
 #include <libxml/parser.h>
+#include <libxml/xmlerror.h>
+#include <libxml/xmlversion.h>
+#include <map>
+#include <memory>
+#include <mutex>
 #include <type_traits>
+#include <utility>
 
 static std::mutex g_ValidatorCacheLock;
 static std::map<const std::string, RelaxNGValidator> g_ValidatorCache;
diff --git a/source/ps/XML/Xeromyces.h b/source/ps/XML/Xeromyces.h
index de6d2ca1b7..4ed79d1aa0 100644
--- a/source/ps/XML/Xeromyces.h
+++ b/source/ps/XML/Xeromyces.h
@@ -1,4 +1,4 @@
-/* Copyright (C) 2024 Wildfire Games.
+/* Copyright (C) 2025 Wildfire Games.
  * This file is part of 0 A.D.
  *
  * 0 A.D. is free software: you can redistribute it and/or modify
@@ -25,19 +25,19 @@
 #define INCLUDED_XEROMYCES
 
 #include "ps/Errors.h"
-ERROR_GROUP(Xeromyces);
-ERROR_TYPE(Xeromyces, XMLOpenFailed);
-ERROR_TYPE(Xeromyces, XMLParseError);
-ERROR_TYPE(Xeromyces, XMLValidationFailed);
-
 #include "ps/Singleton.h"
 #include "ps/XMB/XMBData.h"
 #include "ps/XMB/XMBStorage.h"
 
-#include "lib/file/vfs/vfs.h"
+#include <string>
 
 class RelaxNGValidator;
 
+ERROR_GROUP(Xeromyces);
+ERROR_TYPE(Xeromyces, XMLOpenFailed);
+ERROR_TYPE(Xeromyces, XMLParseError);
+ERROR_TYPE(Xeromyces, XMLValidationFailed);
+
 class CXeromyces : public XMBData
 {
 	friend class TestXMBData;