diff --git a/docs/rh-log.txt b/docs/rh-log.txt
index 01eee2bd3..398180f05 100644
--- a/docs/rh-log.txt
+++ b/docs/rh-log.txt
@@ -1,4 +1,6 @@
 September 5, 2008
+- Added the "extended" keyword for episode definitions to define episodes
+  that are only available in the extended version of Heretic.
 - Added hexendemo.wad and hexdemo.wad as aliases for the demo Hexen IWAD.
 - Added IWAD checks for freedoom1.wad and freedm.wad.
 - The garbage collector now has an opportunity to step each time individual
diff --git a/src/g_level.cpp b/src/g_level.cpp
index a8b3abf83..591bc3b07 100644
--- a/src/g_level.cpp
+++ b/src/g_level.cpp
@@ -1285,6 +1285,7 @@ static void ParseEpisodeInfo (FScanner &sc)
 	char key = 0;
 	bool noskill = false;
 	bool optional = false;
+	bool extended = false;
 
 	// Get map name
 	sc.MustGetString ();
@@ -1305,9 +1306,14 @@ static void ParseEpisodeInfo (FScanner &sc)
 	{
 		if (sc.Compare ("optional"))
 		{
-			// For M4 in Doom and M4 and M5 in Heretic
+			// For M4 in Doom
 			optional = true;
 		}
+		else if (sc.Compare ("extended"))
+		{
+			// For M4 and M5 in Heretic
+			extended = true;
+		}
 		else if (sc.Compare ("name"))
 		{
 			sc.MustGetString ();
@@ -1341,6 +1347,12 @@ static void ParseEpisodeInfo (FScanner &sc)
 	}
 	while (sc.GetString ());
 
+	if (extended && !(gameinfo.flags & GI_MENUHACK_EXTENDED))
+	{ // If the episode is for the extended Heretic, but this is
+	  // not the extended Heretic, ignore it.
+		return;
+	}
+
 	if (optional && !remove)
 	{
 		if (!P_CheckMapData(map))
diff --git a/wadsrc/static/mapinfo/heretic.txt b/wadsrc/static/mapinfo/heretic.txt
index 7050c9f87..a26d7a7a0 100644
--- a/wadsrc/static/mapinfo/heretic.txt
+++ b/wadsrc/static/mapinfo/heretic.txt
@@ -47,12 +47,12 @@ episode e3m1
 episode e4m1 
 	name "$MNU_OSSUARY"
 	key o
-	optional
+	extended
 
 episode e5m1 
 	name "$MNU_DEMESNE"
 	key s
-	optional
+	extended