diff --git a/binaries/data/mods/public/gui/gui.rnc b/binaries/data/mods/mod/gui/gui.rnc
similarity index 100%
rename from binaries/data/mods/public/gui/gui.rnc
rename to binaries/data/mods/mod/gui/gui.rnc
diff --git a/binaries/data/mods/public/gui/gui.rng b/binaries/data/mods/mod/gui/gui.rng
similarity index 100%
rename from binaries/data/mods/public/gui/gui.rng
rename to binaries/data/mods/mod/gui/gui.rng
diff --git a/binaries/data/mods/public/gui/gui_page.rnc b/binaries/data/mods/mod/gui/gui_page.rnc
similarity index 100%
rename from binaries/data/mods/public/gui/gui_page.rnc
rename to binaries/data/mods/mod/gui/gui_page.rnc
diff --git a/binaries/data/mods/public/gui/gui_page.rng b/binaries/data/mods/mod/gui/gui_page.rng
similarity index 100%
rename from binaries/data/mods/public/gui/gui_page.rng
rename to binaries/data/mods/mod/gui/gui_page.rng
diff --git a/source/graphics/MaterialManager.cpp b/source/graphics/MaterialManager.cpp
index e0eaa2cede..74462a0ccd 100644
--- a/source/graphics/MaterialManager.cpp
+++ b/source/graphics/MaterialManager.cpp
@@ -37,7 +37,7 @@ CMaterialManager::CMaterialManager()
 	CFG_GET_VAL("materialmgr.quality", qualityLevel);
 	qualityLevel = clamp(qualityLevel, 0.0f, 10.0f);
 
-	if (!CXeromyces::AddValidator(g_VFS, "material", "art/materials/material.rng"))
+	if (VfsDirectoryExists(L"art/materials/") && !CXeromyces::AddValidator(g_VFS, "material", "art/materials/material.rng"))
 		LOGERROR("CMaterialManager: failed to load grammar file 'art/materials/material.rng'");
 }
 
diff --git a/source/graphics/TerrainTextureManager.cpp b/source/graphics/TerrainTextureManager.cpp
index cb244341d8..0a5497faa4 100644
--- a/source/graphics/TerrainTextureManager.cpp
+++ b/source/graphics/TerrainTextureManager.cpp
@@ -35,9 +35,11 @@
 #include <boost/algorithm/string.hpp>
 
 
-CTerrainTextureManager::CTerrainTextureManager():
-	m_LastGroupIndex(0)
+CTerrainTextureManager::CTerrainTextureManager()
+	: m_LastGroupIndex(0)
 {
+	if (!VfsDirectoryExists(L"art/terrains/"))
+		return;
 	if (!CXeromyces::AddValidator(g_VFS, "terrain", "art/terrains/terrain.rng"))
 		LOGERROR("CTerrainTextureManager: failed to load grammar file 'art/terrains/terrain.rng'");
 	if (!CXeromyces::AddValidator(g_VFS, "terrain_texture", "art/terrains/terrain_texture.rng"))
diff --git a/source/ps/Filesystem.cpp b/source/ps/Filesystem.cpp
index be1610863d..b76ab32e4c 100644
--- a/source/ps/Filesystem.cpp
+++ b/source/ps/Filesystem.cpp
@@ -1,4 +1,4 @@
-/* Copyright (C) 2014 Wildfire Games.
+/* Copyright (C) 2015 Wildfire Games.
  * This file is part of 0 A.D.
  *
  * 0 A.D. is free software: you can redistribute it and/or modify
@@ -35,6 +35,12 @@ bool VfsFileExists(const VfsPath& pathname)
 	return g_VFS->GetFileInfo(pathname, 0) == INFO::OK;
 }
 
+bool VfsDirectoryExists(const VfsPath& pathname)
+{
+	ENSURE(pathname.IsDirectory());
+	return g_VFS->GetDirectoryEntries(pathname, NULL, NULL) == INFO::OK;
+}
+
 void RegisterFileReloadFunc(FileReloadFunc func, void* obj)
 {
 	g_ReloadFuncs.push_back(std::make_pair(func, obj));
diff --git a/source/ps/Filesystem.h b/source/ps/Filesystem.h
index 1eee2440f1..ba87163b41 100644
--- a/source/ps/Filesystem.h
+++ b/source/ps/Filesystem.h
@@ -1,4 +1,4 @@
-/* Copyright (C) 2014 Wildfire Games.
+/* Copyright (C) 2015 Wildfire Games.
  * This file is part of 0 A.D.
  *
  * 0 A.D. is free software: you can redistribute it and/or modify
@@ -30,6 +30,8 @@ extern PIVFS g_VFS;
 
 extern bool VfsFileExists(const VfsPath& pathname);
 
+extern bool VfsDirectoryExists(const VfsPath& pathname);
+
 /**
  * callback function type for file change notifications
  */
diff --git a/source/ps/GameSetup/GameSetup.cpp b/source/ps/GameSetup/GameSetup.cpp
index 13ccd4c48a..a0e86761b4 100644
--- a/source/ps/GameSetup/GameSetup.cpp
+++ b/source/ps/GameSetup/GameSetup.cpp
@@ -1075,7 +1075,8 @@ void InitGraphics(const CmdLineArgs& args, int flags)
 	ogl_WarnIfError();
 
 	// TODO: Is this the best place for this?
-	CXeromyces::AddValidator(g_VFS, "map", "maps/scenario.rng");
+	if (VfsDirectoryExists(L"maps/"))
+		CXeromyces::AddValidator(g_VFS, "map", "maps/scenario.rng");
 
 	try
 	{