diff --git a/src/d_main.cpp b/src/d_main.cpp
index c24b18480..3b1e841a5 100644
--- a/src/d_main.cpp
+++ b/src/d_main.cpp
@@ -1209,8 +1209,11 @@ void D_DoAdvanceDemo (void)
 	case 2:
 		pagetic = (int)(gameinfo.pageTime * TICRATE);
 		gamestate = GS_DEMOSCREEN;
-		pagename = gameinfo.creditPages[pagecount];
-		pagecount = (pagecount+1) % gameinfo.creditPages.Size();
+		if (gameinfo.creditPages.Size() > 0)
+		{
+			pagename = gameinfo.creditPages[pagecount];
+			pagecount = (pagecount+1) % gameinfo.creditPages.Size();
+		}
 		demosequence = 1;
 		break;
 	}
diff --git a/src/g_mapinfo.cpp b/src/g_mapinfo.cpp
index 2b31f50f8..1eb6363fd 100644
--- a/src/g_mapinfo.cpp
+++ b/src/g_mapinfo.cpp
@@ -51,6 +51,8 @@
 #include "doomstat.h"
 #include "d_player.h"
 #include "autosegs.h"
+#include "version.h"
+#include "v_text.h"
 
 int FindEndSequence (int type, const char *picname);
 
@@ -1865,6 +1867,15 @@ void FMapInfoParser::ParseMapInfo (int lump, level_info_t &gamedefaults, level_i
 			{
 				sc.ScriptError("include file '%s' not found", sc.String);
 			}
+			if (Wads.GetLumpFile(sc.LumpNum) != Wads.GetLumpFile(inclump))
+			{
+				// Do not allow overriding includes from the default MAPINFO
+				if (Wads.GetLumpFile(sc.LumpNum) == 0)
+				{
+					I_FatalError("File %s is overriding core lump %s.",
+						Wads.GetWadFullName(Wads.GetLumpFile(inclump)), sc.String);
+				}
+			}
 			FScanner saved_sc = sc;
 			ParseMapInfo(inclump, gamedefaults, defaultinfo);
 			sc = saved_sc;
@@ -1956,12 +1967,18 @@ void G_ParseMapInfo (const char *basemapinfo)
 
 	atterm(ClearEpisodes);
 
-	// Parse the default MAPINFO for the current game.
+	// Parse the default MAPINFO for the current game. This lump *MUST* come from zdoom.pk3.
 	if (basemapinfo != NULL)
 	{
 		FMapInfoParser parse;
 		level_info_t defaultinfo;
-		parse.ParseMapInfo(Wads.GetNumForFullName(basemapinfo), gamedefaults, defaultinfo);
+		int baselump = Wads.GetNumForFullName(basemapinfo);
+		if (Wads.GetLumpFile(baselump) > 0)
+		{
+			I_FatalError("File %s is overriding core lump %s.", 
+				Wads.GetWadFullName(Wads.GetLumpFile(baselump)), basemapinfo);
+		}
+		parse.ParseMapInfo(baselump, gamedefaults, defaultinfo);
 	}
 
 	static const char *mapinfonames[] = { "MAPINFO", "ZMAPINFO", NULL };
diff --git a/src/g_shared/sbarinfo.cpp b/src/g_shared/sbarinfo.cpp
index 1966b58f6..6895ce321 100644
--- a/src/g_shared/sbarinfo.cpp
+++ b/src/g_shared/sbarinfo.cpp
@@ -58,6 +58,7 @@
 #include "v_palette.h"
 #include "p_acs.h"
 #include "gstrings.h"
+#include "version.h"
 
 #define ARTIFLASH_OFFSET (statusBar->invBarOffset+6)
 enum
@@ -469,6 +470,7 @@ void SBarInfo::ParseSBarInfo(int lump)
 			ParseSBarInfo(lump);
 			continue;
 		}
+		int baselump = -2;
 		switch(sc.MustMatchString(SBarInfoTopLevel))
 		{
 			case SBARINFO_BASE:
@@ -477,24 +479,15 @@ void SBarInfo::ParseSBarInfo(int lump)
 					sc.MustGetToken(TK_Identifier);
 				if(sc.Compare("Doom"))
 				{
-					int lump = Wads.CheckNumForFullName("sbarinfo/doom.txt", true);
-					if(lump == -1)
-						sc.ScriptError("Standard Doom Status Bar not found.");
-					ParseSBarInfo(lump);
+					baselump = Wads.CheckNumForFullName("sbarinfo/doom.txt", true);
 				}
 				else if(sc.Compare("Heretic"))
 				{
-					int lump = Wads.CheckNumForFullName("sbarinfo/heretic.txt", true);
-					if(lump == -1)
-						sc.ScriptError("Standard Heretic Status Bar not found.");
-					ParseSBarInfo(lump);
+					baselump = Wads.CheckNumForFullName("sbarinfo/heretic.txt", true);
 				}
 				else if(sc.Compare("Hexen"))
 				{
-					int lump = Wads.CheckNumForFullName("sbarinfo/hexen.txt", true);
-					if(lump == -1)
-						sc.ScriptError("Standard Hexen Status Bar not found.");
-					ParseSBarInfo(lump);
+					baselump = Wads.CheckNumForFullName("sbarinfo/hexen.txt", true);
 				}
 				else if(sc.Compare("Strife"))
 					gameType = GAME_Strife;
@@ -502,6 +495,20 @@ void SBarInfo::ParseSBarInfo(int lump)
 					gameType = GAME_Any;
 				else
 					sc.ScriptError("Bad game name: %s", sc.String);
+				// If one of the standard status bar should be loaded, baselump has been set to a different value.
+				if (baselump != -2)
+				{
+					if(baselump == -1)
+					{
+						sc.ScriptError("Standard %s status bar not found.", sc.String);
+					}
+					else if (Wads.GetLumpFile(baselump) > 0)
+					{
+						I_FatalError("File %s is overriding core lump sbarinfo/%s.txt.",
+							Wads.GetWadFullName(Wads.GetLumpFile(baselump)), sc.String);
+					}
+					ParseSBarInfo(baselump);
+				}
 				sc.MustGetToken(';');
 				break;
 			case SBARINFO_HEIGHT:
diff --git a/src/m_menu.cpp b/src/m_menu.cpp
index 9bc25284e..49d5638ef 100644
--- a/src/m_menu.cpp
+++ b/src/m_menu.cpp
@@ -1293,6 +1293,9 @@ void M_DrawFrame (int left, int top, int width, int height)
 {
 	FTexture *p;
 	const gameborder_t *border = gameinfo.border;
+	// Sanity check for incomplete gameinfo
+	if (border == NULL)
+		return;
 	int offset = border->offset;
 	int right = left + width;
 	int bottom = top + height;
diff --git a/src/thingdef/thingdef_parse.cpp b/src/thingdef/thingdef_parse.cpp
index 7712fe43b..07f4ca4e2 100644
--- a/src/thingdef/thingdef_parse.cpp
+++ b/src/thingdef/thingdef_parse.cpp
@@ -52,6 +52,9 @@
 #include "thingdef_exp.h"
 #include "w_wad.h"
 #include "v_video.h"
+#include "version.h"
+#include "v_text.h"
+#include "m_argv.h"
 
 void ParseOldDecoration(FScanner &sc, EDefinitionType def);
 
@@ -1199,6 +1202,16 @@ void ParseDecorate (FScanner &sc)
 		case TK_Include:
 		{
 			sc.MustGetString();
+			// This check needs to remain overridable for testing purposes.
+			if (Wads.GetLumpFile(sc.LumpNum) == 0 && !Args->CheckParm("-allowdecoratecrossincludes"))
+			{
+				int includefile = Wads.GetLumpFile(Wads.CheckNumForFullName(sc.String, true));
+				if (includefile != 0)
+				{
+					I_FatalError("File %s is overriding core lump %s.",
+						Wads.GetWadFullName(includefile), sc.String);
+				}
+			}
 			FScanner newscanner;
 			newscanner.Open(sc.String);
 			ParseDecorate(newscanner);