diff --git a/source/graphics/Font.h b/source/graphics/Font.h
index 3a739e766e..81de4dd286 100644
--- a/source/graphics/Font.h
+++ b/source/graphics/Font.h
@@ -23,7 +23,6 @@
 
 #include <map>
 
-class CStrW;
 struct UnifontGlyphData;
 
 /**
diff --git a/source/graphics/HeightMipmap.h b/source/graphics/HeightMipmap.h
index 6bdaa47f03..fa764c5a2d 100644
--- a/source/graphics/HeightMipmap.h
+++ b/source/graphics/HeightMipmap.h
@@ -24,7 +24,8 @@
 #ifndef INCLUDED_HEIGHTMIPMAP
 #define INCLUDED_HEIGHTMIPMAP
 
-#include "lib/file/vfs/vfs_path.h"
+class Path;
+using VfsPath = Path;
 
 struct SMipmap
 {
diff --git a/source/graphics/LOSTexture.h b/source/graphics/LOSTexture.h
index 984b64c98b..4c08c5b6ec 100644
--- a/source/graphics/LOSTexture.h
+++ b/source/graphics/LOSTexture.h
@@ -18,11 +18,11 @@
 #include "lib/ogl.h"
 
 #include "maths/Matrix3D.h"
-#include "simulation2/components/ICmpRangeManager.h"
 
 #include "graphics/ShaderManager.h"
+#include "graphics/ShaderTechniquePtr.h"
 
-
+class CLosQuerier;
 class CSimulation2;
 
 /**
diff --git a/source/graphics/MapReader.h b/source/graphics/MapReader.h
index 744c1da839..f7c6e5b08d 100644
--- a/source/graphics/MapReader.h
+++ b/source/graphics/MapReader.h
@@ -19,9 +19,10 @@
 #define INCLUDED_MAPREADER
 
 #include "MapIO.h"
+
+#include "graphics/LightEnv.h"
 #include "lib/res/handle.h"
 #include "ps/CStr.h"
-#include "LightEnv.h"
 #include "ps/FileIo.h"
 #include "scriptinterface/ScriptInterface.h"
 #include "simulation2/system/Entity.h"
diff --git a/source/graphics/ModelDef.h b/source/graphics/ModelDef.h
index 6cebb5c27f..b97d4b8f8c 100644
--- a/source/graphics/ModelDef.h
+++ b/source/graphics/ModelDef.h
@@ -23,6 +23,7 @@
 #define INCLUDED_MODELDEF
 
 #include "ps/CStr.h"
+#include "maths/Matrix3D.h"
 #include "maths/Vector2D.h"
 #include "maths/Vector3D.h"
 #include "maths/Quaternion.h"
diff --git a/source/graphics/ShaderTechnique.h b/source/graphics/ShaderTechnique.h
index fa94b7d197..7b19103d77 100644
--- a/source/graphics/ShaderTechnique.h
+++ b/source/graphics/ShaderTechnique.h
@@ -19,6 +19,7 @@
 #define INCLUDED_SHADERTECHNIQUE
 
 #include "graphics/ShaderProgramPtr.h"
+#include "graphics/ShaderTechniquePtr.h"
 #include "lib/ogl.h"
 
 /**
@@ -110,6 +111,4 @@ private:
 	bool m_SortByDistance;
 };
 
-typedef shared_ptr<CShaderTechnique> CShaderTechniquePtr;
-
 #endif // INCLUDED_SHADERTECHNIQUE
diff --git a/source/graphics/ShaderTechniquePtr.h b/source/graphics/ShaderTechniquePtr.h
new file mode 100644
index 0000000000..7bee0f0cba
--- /dev/null
+++ b/source/graphics/ShaderTechniquePtr.h
@@ -0,0 +1,30 @@
+/* Copyright (C) 2020 Wildfire Games.
+ * This file is part of 0 A.D.
+ *
+ * 0 A.D. is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * 0 A.D. is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with 0 A.D.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+
+
+#ifndef INCLUDED_SHADERTECHNIQUEPTR
+#define INCLUDED_SHADERTECHNIQUEPTR
+
+/*
+ * Forward declaration, to reduce the number of header files that have to pull
+ * in the whole of ShaderTechnique.h
+ */
+class CShaderTechnique;
+typedef std::shared_ptr<CShaderTechnique> CShaderTechniquePtr;
+
+#endif // INCLUDED_SHADERTECHNIQUEPTR
diff --git a/source/graphics/SkeletonAnimDef.cpp b/source/graphics/SkeletonAnimDef.cpp
index 555faccf54..8ed49d0a4d 100644
--- a/source/graphics/SkeletonAnimDef.cpp
+++ b/source/graphics/SkeletonAnimDef.cpp
@@ -23,6 +23,7 @@
 
 #include "SkeletonAnimDef.h"
 #include "maths/MathUtil.h"
+#include "maths/Matrix3D.h"
 #include "ps/FileIo.h"
 
 
diff --git a/source/gui/CGUISprite.h b/source/gui/CGUISprite.h
index 938bf80d4d..23efdb939e 100644
--- a/source/gui/CGUISprite.h
+++ b/source/gui/CGUISprite.h
@@ -25,6 +25,10 @@
 
 #include "gui/GUIRenderer.h"
 #include "gui/SettingTypes/CGUISize.h"
+#include "gui/SettingTypes/CGUIColor.h"
+#include "lib/ogl.h"
+#include "lib/file/vfs/vfs_path.h"
+#include "ps/CStr.h"
 
 #include <map>
 #include <memory>
diff --git a/source/gui/GUIRenderer.h b/source/gui/GUIRenderer.h
index a4a2572b6d..6829be0756 100644
--- a/source/gui/GUIRenderer.h
+++ b/source/gui/GUIRenderer.h
@@ -18,17 +18,19 @@
 #ifndef INCLUDED_GUIRENDERER
 #define INCLUDED_GUIRENDERER
 
-#include "graphics/ShaderTechnique.h"
+#include "graphics/Color.h"
+#include "graphics/ShaderTechniquePtr.h"
 #include "graphics/Texture.h"
-#include "gui/SettingTypes/CGUIColor.h"
 #include "lib/res/handle.h"
-#include "ps/CStr.h"
 #include "ps/Shapes.h"
 
 #include <map>
 #include <vector>
 
+class CGUI;
 class CGUISprite;
+class CStr8;
+struct CGUIColor;
 struct SGUIImage;
 
 namespace GUIRenderer
@@ -67,7 +69,7 @@ namespace GUIRenderer
 		DrawCalls& operator=(const DrawCalls&);
 	};
 
-	void UpdateDrawCallCache(const CGUI& pGUI, DrawCalls& Calls, const CStr& SpriteName, const CRect& Size, int CellID, std::map<CStr, const CGUISprite*>& Sprites);
+	void UpdateDrawCallCache(const CGUI& pGUI, DrawCalls& Calls, const CStr8& SpriteName, const CRect& Size, int CellID, std::map<CStr8, const CGUISprite*>& Sprites);
 
 	void Draw(DrawCalls& Calls, float Z);
 }
diff --git a/source/gui/IGUIScrollBar.h b/source/gui/IGUIScrollBar.h
index 32d1b5bb68..5a55e1dedb 100644
--- a/source/gui/IGUIScrollBar.h
+++ b/source/gui/IGUIScrollBar.h
@@ -25,7 +25,9 @@
 #define INCLUDED_IGUISCROLLBAR
 
 #include "gui/CGUISprite.h"
+#include "ps/CStr.h"
 
+class CGUI;
 class IGUIScrollBarOwner;
 struct SGUIMessage;
 
diff --git a/source/gui/ObjectBases/IGUIButtonBehavior.h b/source/gui/ObjectBases/IGUIButtonBehavior.h
index 4559a99220..e1a7c9f239 100644
--- a/source/gui/ObjectBases/IGUIButtonBehavior.h
+++ b/source/gui/ObjectBases/IGUIButtonBehavior.h
@@ -27,6 +27,7 @@
 #define INCLUDED_IGUIBUTTONBEHAVIOR
 
 #include "gui/ObjectBases/IGUIObject.h"
+#include "ps/CStr.h"
 
 class CGUISpriteInstance;
 
diff --git a/source/gui/ObjectTypes/CHotkeyPicker.h b/source/gui/ObjectTypes/CHotkeyPicker.h
index 0c41f39b0f..fdffef8ffb 100644
--- a/source/gui/ObjectTypes/CHotkeyPicker.h
+++ b/source/gui/ObjectTypes/CHotkeyPicker.h
@@ -32,8 +32,6 @@ class ScriptInterface;
  *
  * Used to create new hotkey combinations in-game. Mostly custom.
  * This object does not draw anything.
- *
- * NB: because of how input is handled, mouse clicks
  */
 class CHotkeyPicker : public IGUIObject
 {
diff --git a/source/gui/ObjectTypes/CMiniMap.cpp b/source/gui/ObjectTypes/CMiniMap.cpp
index d96bc6b4fe..ba69152007 100644
--- a/source/gui/ObjectTypes/CMiniMap.cpp
+++ b/source/gui/ObjectTypes/CMiniMap.cpp
@@ -46,6 +46,7 @@
 #include "scriptinterface/ScriptInterface.h"
 #include "simulation2/Simulation2.h"
 #include "simulation2/components/ICmpMinimap.h"
+#include "simulation2/components/ICmpRangeManager.h"
 #include "simulation2/helpers/Los.h"
 #include "simulation2/system/ParamNode.h"
 
diff --git a/source/gui/SettingTypes/CGUIColor.h b/source/gui/SettingTypes/CGUIColor.h
index c82ed09108..0c4006f6e0 100644
--- a/source/gui/SettingTypes/CGUIColor.h
+++ b/source/gui/SettingTypes/CGUIColor.h
@@ -19,9 +19,9 @@
 #define INCLUDED_GUICOLOR
 
 #include "graphics/Color.h"
-#include "ps/CStr.h"
 
 class CGUI;
+class CStr8;
 
 /**
  * Same as the CColor class, but this one can also parse colors predefined in the GUI page (such as "yellow").
@@ -51,11 +51,11 @@ struct CGUIColor : CColor
 	/**
 	 * Load color depending on current GUI page.
 	 */
-	bool ParseString(const CGUI& pGUI, const CStr& value, int defaultAlpha = 255);
+	bool ParseString(const CGUI& pGUI, const CStr8& value, int defaultAlpha = 255);
 
 	/**
 	 * Ensure that all users check for predefined colors.
 	 */
-	bool ParseString(const CStr& value, int defaultAlpha = 255) = delete;
+	bool ParseString(const CStr8& value, int defaultAlpha = 255) = delete;
 };
 #endif // INCLUDED_GUICOLOR
diff --git a/source/gui/SettingTypes/CGUISize.h b/source/gui/SettingTypes/CGUISize.h
index e547be78ba..e033c626fc 100644
--- a/source/gui/SettingTypes/CGUISize.h
+++ b/source/gui/SettingTypes/CGUISize.h
@@ -18,9 +18,10 @@
 #ifndef INCLUDED_CGUISIZE
 #define INCLUDED_CGUISIZE
 
-#include "ps/CStr.h"
 #include "ps/Shapes.h"
-#include "scriptinterface/ScriptInterface.h"
+#include "scriptinterface/ScriptForward.h"
+
+class CStr8;
 
 /**
  * This class represents a rectangle relative to a parent rectangle
@@ -60,7 +61,7 @@ public:
 	 *
 	 * @return true if success, otherwise size will remain unchanged.
 	 */
-	bool FromString(const CStr& Value);
+	bool FromString(const CStr8& Value);
 
 	bool operator==(const CGUISize& other) const
 	{
diff --git a/source/lib/secure_crt.h b/source/lib/secure_crt.h
index 1eaa8f7247..d059e01bd2 100644
--- a/source/lib/secure_crt.h
+++ b/source/lib/secure_crt.h
@@ -52,8 +52,8 @@ namespace ERR
 // null character. to protect against access violations, only the
 // first <max_len> characters are examined; if the null character is
 // not encountered by then, <max_len> is returned.
-// strnlen is available on OpenBSD
-#if !OS_OPENBSD
+// strnlen is available on OpenBSD and MacOS
+#if !OS_OPENBSD && !OS_MACOSX
 extern size_t strnlen(const char* str, size_t max_len);
 #endif
 extern size_t wcsnlen(const wchar_t* str, size_t max_len);
diff --git a/source/lib/sysdep/os/osx/osx_stl_fixes.h b/source/lib/sysdep/os/osx/osx_stl_fixes.h
deleted file mode 100644
index d4371c2a19..0000000000
--- a/source/lib/sysdep/os/osx/osx_stl_fixes.h
+++ /dev/null
@@ -1,121 +0,0 @@
-/* Copyright (C) 2013 Wildfire Games.
- *
- * Permission is hereby granted, free of charge, to any person obtaining
- * a copy of this software and associated documentation files (the
- * "Software"), to deal in the Software without restriction, including
- * without limitation the rights to use, copy, modify, merge, publish,
- * distribute, sublicense, and/or sell copies of the Software, and to
- * permit persons to whom the Software is furnished to do so, subject to
- * the following conditions:
- *
- * The above copyright notice and this permission notice shall be included
- * in all copies or substantial portions of the Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
- * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
- * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
- * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
- * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
- * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
- * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
- */
-
-#ifndef OSX_STL_FIXES_H
-#define OSX_STL_FIXES_H
-
-#include <istream>
-#include <ostream>
-#include <AvailabilityMacros.h> // MAC_OS_X_VERSION_*
-
-/**
- * This file adds some explicit template instantiations that are
- * declared external on 10.6+ SDKs but are missing from stdc++ on 10.5
- * (this causes a failure to load due to missing symbols on 10.5)
- **/
-
-#if MAC_OS_X_VERSION_MAX_ALLOWED >= 1060 && MAC_OS_X_VERSION_MIN_REQUIRED < 1060
-
-_GLIBCXX_BEGIN_NAMESPACE(std)
-
-
-// ostream_insert.h:
-# if _GLIBCXX_EXTERN_TEMPLATE
-	template ostream& __ostream_insert(ostream&, const char*, streamsize);
-#  ifdef _GLIBCXX_USE_WCHAR_T
-	template wostream& __ostream_insert(wostream&, const wchar_t*,
-					streamsize);
-#  endif
-# endif
-
-
-// istream.tcc:
-# if _GLIBCXX_EXTERN_TEMPLATE
-  template istream& istream::_M_extract(unsigned short&);
-  template istream& istream::_M_extract(unsigned int&);
-  template istream& istream::_M_extract(long&);
-  template istream& istream::_M_extract(unsigned long&);
-  template istream& istream::_M_extract(bool&);
-#  ifdef _GLIBCXX_USE_LONG_LONG
-  template istream& istream::_M_extract(long long&);
-  template istream& istream::_M_extract(unsigned long long&);
-#  endif
-  template istream& istream::_M_extract(float&);
-  template istream& istream::_M_extract(double&);
-  template istream& istream::_M_extract(long double&);
-  template istream& istream::_M_extract(void*&);
-
-  template class basic_iostream<char>;
-
-#  ifdef _GLIBCXX_USE_WCHAR_T
-  template wistream& wistream::_M_extract(unsigned short&);
-  template wistream& wistream::_M_extract(unsigned int&);
-  template wistream& wistream::_M_extract(long&);
-  template wistream& wistream::_M_extract(unsigned long&);
-  template wistream& wistream::_M_extract(bool&);
-#   ifdef _GLIBCXX_USE_LONG_LONG
-  template wistream& wistream::_M_extract(long long&);
-  template wistream& wistream::_M_extract(unsigned long long&);
-#   endif
-  template wistream& wistream::_M_extract(float&);
-  template wistream& wistream::_M_extract(double&);
-  template wistream& wistream::_M_extract(long double&);
-  template wistream& wistream::_M_extract(void*&);
-
-  template class basic_iostream<wchar_t>;
-#  endif
-# endif
-
-
-// ostream.tcc:
-# if _GLIBCXX_EXTERN_TEMPLATE
-  template ostream& ostream::_M_insert(long);
-  template ostream& ostream::_M_insert(unsigned long);
-  template ostream& ostream::_M_insert(bool);
-#  ifdef _GLIBCXX_USE_LONG_LONG
-  template ostream& ostream::_M_insert(long long);
-  template ostream& ostream::_M_insert(unsigned long long);
-#  endif
-  template ostream& ostream::_M_insert(double);
-  template ostream& ostream::_M_insert(long double);
-  template ostream& ostream::_M_insert(const void*);
-
-#  ifdef _GLIBCXX_USE_WCHAR_T
-  template wostream& wostream::_M_insert(long);
-  template wostream& wostream::_M_insert(unsigned long);
-  template wostream& wostream::_M_insert(bool);
-#   ifdef _GLIBCXX_USE_LONG_LONG
-  template wostream& wostream::_M_insert(long long);
-  template wostream& wostream::_M_insert(unsigned long long);
-#   endif
-  template wostream& wostream::_M_insert(double);
-  template wostream& wostream::_M_insert(long double);
-  template wostream& wostream::_M_insert(const void*);
-#  endif
-# endif
-
-
-_GLIBCXX_END_NAMESPACE
-
-#endif // MAC_OS_X_VERSION_MAX_ALLOWED >= 1060 && MAC_OS_X_VERSION_MIN_REQUIRED < 1060
-
-#endif // OSX_STL_FIXES_H
diff --git a/source/lib/sysdep/stl.h b/source/lib/sysdep/stl.h
index f4caa3ca48..350984d2be 100644
--- a/source/lib/sysdep/stl.h
+++ b/source/lib/sysdep/stl.h
@@ -72,10 +72,4 @@
 # endif
 #endif
 
-
-// OS X - fix some stream template instantiations that break 10.5 compatibility on newer SDKs
-#if OS_MACOSX
-# include "os/osx/osx_stl_fixes.h"
-#endif
-
 #endif	// #ifndef INCLUDED_STL
diff --git a/source/maths/Quaternion.cpp b/source/maths/Quaternion.cpp
index e8d5863192..1aac49b6fa 100644
--- a/source/maths/Quaternion.cpp
+++ b/source/maths/Quaternion.cpp
@@ -18,7 +18,9 @@
 #include "precompiled.h"
 
 #include "Quaternion.h"
+
 #include "MathUtil.h"
+#include "Matrix3D.h"
 
 const float EPSILON=0.0001f;
 
diff --git a/source/maths/Quaternion.h b/source/maths/Quaternion.h
index d63852ffa4..c0574122d0 100644
--- a/source/maths/Quaternion.h
+++ b/source/maths/Quaternion.h
@@ -18,9 +18,10 @@
 #ifndef INCLUDED_QUATERNION
 #define INCLUDED_QUATERNION
 
-#include "Matrix3D.h"
 #include "Vector3D.h"
 
+class CMatrix3D;
+
 class CQuaternion
 {
 public:
diff --git a/source/network/NetServerTurnManager.cpp b/source/network/NetServerTurnManager.cpp
index f16e749931..7b15b25116 100644
--- a/source/network/NetServerTurnManager.cpp
+++ b/source/network/NetServerTurnManager.cpp
@@ -22,6 +22,7 @@
 #include "NetServer.h"
 #include "NetSession.h"
 
+#include "lib/utf8.h"
 #include "ps/CLogger.h"
 #include "simulation2/system/TurnManager.h"
 
diff --git a/source/ps/FileIo.h b/source/ps/FileIo.h
index 9426c6e73e..b3cc06ec3a 100644
--- a/source/ps/FileIo.h
+++ b/source/ps/FileIo.h
@@ -30,11 +30,13 @@
 #ifndef INCLUDED_FILEPACKER
 #define INCLUDED_FILEPACKER
 
-#include "CStr.h"
 #include "lib/file/vfs/vfs_path.h"
 #include "ps/Filesystem.h"	// WriteBuffer
 
 #include "ps/Errors.h"
+
+class CStr8;
+
 ERROR_GROUP(File);
 ERROR_TYPE(File, OpenFailed);
 ERROR_TYPE(File, WriteFailed);
@@ -83,7 +85,7 @@ public:
 	 * pack a string onto the end of the data stream
 	 * (encoded as a 32-bit length followed by the characters)
 	 **/
-	void PackString(const CStr& str);
+	void PackString(const CStr8& str);
 
 private:
 	/**
diff --git a/source/ps/Filesystem.h b/source/ps/Filesystem.h
index ba87163b41..333e934a25 100644
--- a/source/ps/Filesystem.h
+++ b/source/ps/Filesystem.h
@@ -23,9 +23,10 @@
 #include "lib/file/io/write_buffer.h"
 #include "lib/file/vfs/vfs_util.h"
 
-#include "ps/CStr.h"
 #include "ps/Errors.h"
 
+class CStr8;
+
 extern PIVFS g_VFS;
 
 extern bool VfsFileExists(const VfsPath& pathname);
@@ -92,13 +93,13 @@ public:
 	 * Returns contents of file as a string
 	 * @note file must have been successfully loaded
 	 */
-	CStr GetAsString() const;
+	CStr8 GetAsString() const;
 
 	/**
 	 * Returns contents of a UTF-8 encoded file as a string with optional BOM removed
 	 * @note file must have been successfully loaded
 	 */
-	CStr DecodeUTF8() const;
+	CStr8 DecodeUTF8() const;
 
 private:
 	shared_ptr<u8> m_Buffer;
diff --git a/source/ps/GUID.h b/source/ps/GUID.h
index a8c405d9a1..41a8252c77 100644
--- a/source/ps/GUID.h
+++ b/source/ps/GUID.h
@@ -18,8 +18,8 @@
 #ifndef INCLUDED_GUID
 #define INCLUDED_GUID
 
-#include "ps/CStr.h"
+class CStr8;
 
-CStr ps_generate_guid(void);
+CStr8 ps_generate_guid(void);
 
 #endif
diff --git a/source/ps/Game.h b/source/ps/Game.h
index e888008f87..b6c7429ec7 100644
--- a/source/ps/Game.h
+++ b/source/ps/Game.h
@@ -20,6 +20,7 @@
 
 #include <vector>
 
+#include "ps/CStr.h"
 #include "ps/Errors.h"
 #include "ps/Filesystem.h"
 #include "scriptinterface/ScriptTypes.h"
diff --git a/source/ps/Profile.h b/source/ps/Profile.h
index a404f381a1..e914e613be 100644
--- a/source/ps/Profile.h
+++ b/source/ps/Profile.h
@@ -40,9 +40,6 @@
 class CProfileManager;
 class CProfileNodeTable;
 
-class CStr8;
-class CStrW;
-
 // To profile scripts usefully, we use a call hook that's called on every enter/exit,
 // and need to find the function name. But most functions are anonymous so we make do
 // with filename plus line number instead.
diff --git a/source/ps/XML/XMLWriter.h b/source/ps/XML/XMLWriter.h
index c243670484..0155d089f3 100644
--- a/source/ps/XML/XMLWriter.h
+++ b/source/ps/XML/XMLWriter.h
@@ -61,9 +61,9 @@
  *	end of XMLWriter.cpp.
  */
 
-#include "ps/CStr.h"
 #include "lib/file/vfs/vfs.h"
 
+class CStr8;
 class XMBElement;
 class XMBFile;
 class XMLWriter_Element;
@@ -80,7 +80,7 @@ public:
 	void XMB(const XMBFile& file);
 
 	bool StoreVFS(const PIVFS& vfs, const VfsPath& pathname);
-	const CStr& GetOutput();
+	const CStr8& GetOutput();
 
 private:
 
@@ -94,11 +94,11 @@ private:
 	void ElementClose();
 	void ElementEnd(const char* name, int type);
 
-	CStr Indent();
+	CStr8 Indent();
 
 	bool m_PrettyPrint;
 
-	CStr m_Data;
+	CStr8 m_Data;
 	int m_Indent;
 	XMLWriter_Element* m_LastElement;
 };
@@ -119,7 +119,7 @@ private:
 	friend class XMLWriter_File;
 
 	XMLWriter_File* m_File;
-	CStr m_Name;
+	CStr8 m_Name;
 	int m_Type;
 };
 
diff --git a/source/renderer/PostprocManager.h b/source/renderer/PostprocManager.h
index 19698f65ee..ed7e19a536 100644
--- a/source/renderer/PostprocManager.h
+++ b/source/renderer/PostprocManager.h
@@ -18,7 +18,8 @@
 #ifndef INCLUDED_POSTPROCMANAGER
 #define INCLUDED_POSTPROCMANAGER
 
-#include "graphics/ShaderTechnique.h"
+#include "graphics/ShaderTechniquePtr.h"
+#include "lib/ogl.h"
 #include "ps/CStr.h"
 
 #include <vector>
diff --git a/source/scriptinterface/ScriptForward.h b/source/scriptinterface/ScriptForward.h
new file mode 100644
index 0000000000..eeace49384
--- /dev/null
+++ b/source/scriptinterface/ScriptForward.h
@@ -0,0 +1,26 @@
+/* Copyright (C) 2020 Wildfire Games.
+ * This file is part of 0 A.D.
+ *
+ * 0 A.D. is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * 0 A.D. is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with 0 A.D.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef INCLUDED_SCRIPTFORWARD
+#define INCLUDED_SCRIPTFORWARD
+
+#include "js/TypeDecls.h"
+
+class ScriptInterface;
+class ScriptRequest;
+
+#endif // INCLUDED_SCRIPTFORWARD
diff --git a/source/simulation2/components/CCmpSelectable.cpp b/source/simulation2/components/CCmpSelectable.cpp
index 219e171737..b5d7513861 100644
--- a/source/simulation2/components/CCmpSelectable.cpp
+++ b/source/simulation2/components/CCmpSelectable.cpp
@@ -27,6 +27,7 @@
 #include "maths/Matrix3D.h"
 #include "maths/Vector3D.h"
 #include "maths/Vector2D.h"
+#include "ps/CLogger.h"
 #include "ps/Profile.h"
 #include "renderer/Scene.h"
 #include "renderer/Renderer.h"
diff --git a/source/simulation2/components/ICmpObstructionManager.h b/source/simulation2/components/ICmpObstructionManager.h
index 1c656d1ee1..97ada2a035 100644
--- a/source/simulation2/components/ICmpObstructionManager.h
+++ b/source/simulation2/components/ICmpObstructionManager.h
@@ -20,14 +20,16 @@
 
 #include "simulation2/system/Interface.h"
 
-#include "simulation2/helpers/Pathfinding.h"
-
 #include "maths/FixedVector2D.h"
+#include "simulation2/helpers/Position.h"
 
 class IObstructionTestFilter;
 template<typename T>
 class Grid;
 struct GridUpdateInformation;
+using NavcellData = u16;
+class PathfinderPassability;
+
 
 /**
  * Obstruction manager: provides efficient spatial queries over objects in the world.
diff --git a/source/simulation2/components/ICmpPathfinder.h b/source/simulation2/components/ICmpPathfinder.h
index dcf9847eff..cc07011832 100644
--- a/source/simulation2/components/ICmpPathfinder.h
+++ b/source/simulation2/components/ICmpPathfinder.h
@@ -21,7 +21,6 @@
 #include "simulation2/system/Interface.h"
 
 #include "simulation2/components/ICmpObstruction.h"
-#include "simulation2/helpers/PathGoal.h"
 #include "simulation2/helpers/Pathfinding.h"
 
 #include "maths/FixedVector2D.h"
@@ -30,6 +29,7 @@
 #include <vector>
 
 class IObstructionTestFilter;
+class PathGoal;
 
 template<typename T> class Grid;
 
diff --git a/source/simulation2/components/tests/test_Position.h b/source/simulation2/components/tests/test_Position.h
index 96e3f885f3..0b9d137ced 100644
--- a/source/simulation2/components/tests/test_Position.h
+++ b/source/simulation2/components/tests/test_Position.h
@@ -17,6 +17,7 @@
 
 #include "simulation2/system/ComponentTest.h"
 
+#include "maths/Matrix3D.h"
 #include "simulation2/components/ICmpPosition.h"
 #include "simulation2/components/ICmpWaterManager.h"
 
diff --git a/source/simulation2/components/tests/test_RangeManager.h b/source/simulation2/components/tests/test_RangeManager.h
index 321494d708..dde0c68515 100644
--- a/source/simulation2/components/tests/test_RangeManager.h
+++ b/source/simulation2/components/tests/test_RangeManager.h
@@ -15,6 +15,7 @@
  * along with 0 A.D.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include "maths/Matrix3D.h"
 #include "simulation2/system/ComponentTest.h"
 #include "simulation2/components/ICmpRangeManager.h"
 #include "simulation2/components/ICmpObstruction.h"
diff --git a/source/simulation2/helpers/HierarchicalPathfinder.h b/source/simulation2/helpers/HierarchicalPathfinder.h
index 87eb97d714..003fadf1a3 100644
--- a/source/simulation2/helpers/HierarchicalPathfinder.h
+++ b/source/simulation2/helpers/HierarchicalPathfinder.h
@@ -20,6 +20,7 @@
 
 #include "Pathfinding.h"
 
+#include "ps/CLogger.h"
 #include "renderer/TerrainOverlay.h"
 #include "Render.h"
 #include "graphics/SColor.h"
diff --git a/source/simulation2/helpers/Pathfinding.cpp b/source/simulation2/helpers/Pathfinding.cpp
index 31f84e320d..fcfd353c08 100644
--- a/source/simulation2/helpers/Pathfinding.cpp
+++ b/source/simulation2/helpers/Pathfinding.cpp
@@ -20,7 +20,9 @@
 #include "Pathfinding.h"
 
 #include "graphics/Terrain.h"
-#include "Grid.h"
+#include "ps/CLogger.h"
+#include "simulation2/helpers/Grid.h"
+#include "simulation2/system/ParamNode.h"
 
 namespace Pathfinding
 {
diff --git a/source/simulation2/helpers/Pathfinding.h b/source/simulation2/helpers/Pathfinding.h
index 8cefaa96b2..a7dab4a387 100644
--- a/source/simulation2/helpers/Pathfinding.h
+++ b/source/simulation2/helpers/Pathfinding.h
@@ -20,12 +20,12 @@
 
 #include "graphics/Terrain.h"
 #include "maths/MathUtil.h"
-#include "ps/CLogger.h"
 
 #include "simulation2/system/Entity.h"
-#include "simulation2/system/ParamNode.h"
 #include "PathGoal.h"
 
+class CParamNode;
+
 typedef u16 pass_class_t;
 template<typename T>
 class Grid;
diff --git a/source/simulation2/helpers/Rasterize.cpp b/source/simulation2/helpers/Rasterize.cpp
index 9037300b68..c8ad5b606e 100644
--- a/source/simulation2/helpers/Rasterize.cpp
+++ b/source/simulation2/helpers/Rasterize.cpp
@@ -20,6 +20,7 @@
 #include "Rasterize.h"
 
 #include "simulation2/helpers/Geometry.h"
+#include "simulation2/helpers/Pathfinding.h"
 
 void SimRasterize::RasterizeRectWithClearance(Spans& spans,
 	const ICmpObstructionManager::ObstructionSquare& shape,
diff --git a/source/simulation2/helpers/Rasterize.h b/source/simulation2/helpers/Rasterize.h
index bfee13ce8b..d1c6423b85 100644
--- a/source/simulation2/helpers/Rasterize.h
+++ b/source/simulation2/helpers/Rasterize.h
@@ -24,6 +24,7 @@
  */
 
 #include "simulation2/components/ICmpObstructionManager.h"
+#include "simulation2/helpers/Position.h"
 
 namespace SimRasterize
 {
diff --git a/source/simulation2/helpers/Render.cpp b/source/simulation2/helpers/Render.cpp
index e5d6db66d3..5c29ebdb97 100644
--- a/source/simulation2/helpers/Render.cpp
+++ b/source/simulation2/helpers/Render.cpp
@@ -24,6 +24,7 @@
 #include "maths/BoundingBoxAligned.h"
 #include "maths/BoundingBoxOriented.h"
 #include "maths/MathUtil.h"
+#include "maths/Matrix3D.h"
 #include "maths/Quaternion.h"
 #include "maths/Vector2D.h"
 #include "ps/Profile.h"
diff --git a/source/simulation2/helpers/Selection.h b/source/simulation2/helpers/Selection.h
index 24bc2a4561..26158dfb49 100644
--- a/source/simulation2/helpers/Selection.h
+++ b/source/simulation2/helpers/Selection.h
@@ -19,10 +19,10 @@
 #define INCLUDED_SELECTION
 
 #include "ps/Profiler2.h"
-#include "simulation2/components/ICmpObstruction.h"
 #include "simulation2/helpers/Player.h"
 #include "simulation2/Simulation2.h"
 #include "simulation2/system/Entity.h"
+#include "simulation2/system/IComponent.h"
 
 #include <vector>
 
diff --git a/source/simulation2/helpers/SimulationCommand.h b/source/simulation2/helpers/SimulationCommand.h
index 8845cfa39f..17e184deba 100644
--- a/source/simulation2/helpers/SimulationCommand.h
+++ b/source/simulation2/helpers/SimulationCommand.h
@@ -18,7 +18,7 @@
 #ifndef INCLUDED_SIMULATIONCOMMAND
 #define INCLUDED_SIMULATIONCOMMAND
 
-#include "scriptinterface/ScriptInterface.h"
+#include "scriptinterface/ScriptTypes.h"
 #include "simulation2/helpers/Player.h"
 
 /**
diff --git a/source/simulation2/scripting/JSInterface_Simulation.cpp b/source/simulation2/scripting/JSInterface_Simulation.cpp
index b006fceee9..543afa7772 100644
--- a/source/simulation2/scripting/JSInterface_Simulation.cpp
+++ b/source/simulation2/scripting/JSInterface_Simulation.cpp
@@ -28,6 +28,7 @@
 #include "simulation2/components/ICmpAIManager.h"
 #include "simulation2/components/ICmpCommandQueue.h"
 #include "simulation2/components/ICmpGuiInterface.h"
+#include "simulation2/components/ICmpObstruction.h"
 #include "simulation2/components/ICmpPosition.h"
 #include "simulation2/components/ICmpSelectable.h"
 #include "simulation2/helpers/Geometry.h"
diff --git a/source/simulation2/system/ComponentTest.h b/source/simulation2/system/ComponentTest.h
index 88d978d227..5542758a43 100644
--- a/source/simulation2/system/ComponentTest.h
+++ b/source/simulation2/system/ComponentTest.h
@@ -20,7 +20,6 @@
 
 #include "lib/self_test.h"
 
-#include "maths/Matrix3D.h"
 #include "maths/Vector3D.h"
 #include "ps/XML/Xeromyces.h"
 #include "simulation2/MessageTypes.h"
diff --git a/source/simulation2/system/IComponent.h b/source/simulation2/system/IComponent.h
index 9743692c2a..0d5515b2f1 100644
--- a/source/simulation2/system/IComponent.h
+++ b/source/simulation2/system/IComponent.h
@@ -22,8 +22,7 @@
 #include "Message.h"
 #include "Entity.h"
 #include "SimContext.h"
-
-#include "scriptinterface/ScriptTypes.h"
+#include "scriptinterface/ScriptForward.h"
 
 class CParamNode;
 class CMessage;
diff --git a/source/tools/atlas/GameInterface/ActorViewer.h b/source/tools/atlas/GameInterface/ActorViewer.h
index da932d10c0..1740b49a7e 100644
--- a/source/tools/atlas/GameInterface/ActorViewer.h
+++ b/source/tools/atlas/GameInterface/ActorViewer.h
@@ -18,13 +18,14 @@
 #ifndef INCLUDED_ACTORVIEWER
 #define INCLUDED_ACTORVIEWER
 
-#include "ps/CStr.h"
 #include "simulation2/helpers/Player.h"
 #include "simulation2/system/Entity.h"
 
 struct ActorViewerImpl;
 struct SColor4ub;
 class CSimulation2;
+class CStr8;
+class CStrW;
 
 class ActorViewer
 {
@@ -35,7 +36,7 @@ public:
 
 	CSimulation2* GetSimulation2();
 	entity_id_t GetEntity();
-	void SetActor(const CStrW& id, const CStr& animation, player_id_t playerID);
+	void SetActor(const CStrW& id, const CStr8& animation, player_id_t playerID);
 	void SetEnabled(bool enabled);
 	void UnloadObjects();
 	void SetBackgroundColor(const SColor4ub& color);
diff --git a/source/tools/atlas/GameInterface/Handlers/MapHandlers.cpp b/source/tools/atlas/GameInterface/Handlers/MapHandlers.cpp
index d5b0f2a9ef..b5561d7ae8 100644
--- a/source/tools/atlas/GameInterface/Handlers/MapHandlers.cpp
+++ b/source/tools/atlas/GameInterface/Handlers/MapHandlers.cpp
@@ -40,6 +40,7 @@
 #include "ps/Game.h"
 #include "ps/GameSetup/GameSetup.h"
 #include "ps/Loader.h"
+#include "ps/Shapes.h"
 #include "ps/World.h"
 #include "renderer/Renderer.h"
 #include "renderer/WaterManager.h"