diff --git a/src/gi.cpp b/src/gi.cpp
index 8dea1e577a..85335554cf 100644
--- a/src/gi.cpp
+++ b/src/gi.cpp
@@ -371,6 +371,7 @@ void FMapInfoParser::ParseGameInfo()
 		GAMEINFOKEY_STRING_STAMPED(statusbarclass, "statusbarclass", statusbarclassfile)
 		GAMEINFOKEY_MUSIC(intermissionMusic, intermissionOrder, "intermissionMusic")
 		GAMEINFOKEY_STRING(CursorPic, "CursorPic")
+		GAMEINFOKEY_STRING(MessageBoxClass, "MessageBoxClass")
 		GAMEINFOKEY_BOOL(noloopfinalemusic, "noloopfinalemusic")
 		GAMEINFOKEY_BOOL(drawreadthis, "drawreadthis")
 		GAMEINFOKEY_BOOL(swapmenu, "swapmenu")
diff --git a/src/gi.h b/src/gi.h
index d656e80bfa..5c9dc1ae58 100644
--- a/src/gi.h
+++ b/src/gi.h
@@ -152,6 +152,7 @@ struct gameinfo_t
 	int statusbarfile = -1;
 	FName statusbarclass;
 	int statusbarclassfile = -1;
+	FName MessageBoxClass;
 	FName backpacktype;
 	FString intermissionMusic;
 	int intermissionOrder;
diff --git a/src/menu/messagebox.cpp b/src/menu/messagebox.cpp
index 3684209646..3531cf2f62 100644
--- a/src/menu/messagebox.cpp
+++ b/src/menu/messagebox.cpp
@@ -66,14 +66,18 @@ DEFINE_ACTION_FUNCTION(DMessageBoxMenu, CallHandler)
 
 DMenu *CreateMessageBoxMenu(DMenu *parent, const char *message, int messagemode, bool playsound, FName action = NAME_None, hfunc handler = nullptr)
 {
-	auto c = PClass::FindClass("MessageBoxMenu");
+	auto c = PClass::FindClass(gameinfo.MessageBoxClass);
+	if (!c->IsDescendantOf(NAME_MessageBoxMenu)) c = PClass::FindClass(NAME_MessageBoxMenu);
 	auto p = c->CreateNew();
 	FString namestr = message;
-	VMValue params[] = { p, parent, &namestr, messagemode, playsound, action.GetIndex(), reinterpret_cast<void*>(handler) };
 
-	auto f = dyn_cast<PFunction>(c->FindSymbol("Init", false));
-	VMCall(f->Variants[0].Implementation, params, countof(params), nullptr, 0);
-	return (DMenu*)p;
+	IFVIRTUALPTRNAME(p, NAME_MessageBoxMenu, Init)
+	{
+		VMValue params[] = { p, parent, &namestr, messagemode, playsound, action.GetIndex(), reinterpret_cast<void*>(handler) };
+		VMCall(func, params, countof(params), nullptr, 0);
+		return (DMenu*)p;
+	}
+	return nullptr;
 }
 
 //=============================================================================
diff --git a/src/namedef.h b/src/namedef.h
index bfbf263622..ad29da9ba7 100644
--- a/src/namedef.h
+++ b/src/namedef.h
@@ -912,3 +912,4 @@ xx(StaticArray)
 xx(DynArray)
 xx(Struct)
 xx(ReflectType)
+xx(MessageBoxMenu)
diff --git a/wadsrc/static/mapinfo/chex.txt b/wadsrc/static/mapinfo/chex.txt
index 4bff1283ec..fe852542f4 100644
--- a/wadsrc/static/mapinfo/chex.txt
+++ b/wadsrc/static/mapinfo/chex.txt
@@ -68,6 +68,7 @@ gameinfo
 	statscreen_coop = "CoopStatusScreen"
 	statscreen_dm = "DeathmatchStatusScreen"
 	statscreen_single = "DoomStatusScreen"
+	messageboxclass = "MessageBoxMenu"
 }
 
 DoomEdNums
diff --git a/wadsrc/static/mapinfo/doomcommon.txt b/wadsrc/static/mapinfo/doomcommon.txt
index c033ce09c0..82eb14d22f 100644
--- a/wadsrc/static/mapinfo/doomcommon.txt
+++ b/wadsrc/static/mapinfo/doomcommon.txt
@@ -69,6 +69,7 @@ gameinfo
 	statscreen_coop = "CoopStatusScreen"
 	statscreen_dm = "DeathmatchStatusScreen"
 	statscreen_single = "DoomStatusScreen"
+	messageboxclass = "MessageBoxMenu"
 }
 
 spawnnums
diff --git a/wadsrc/static/mapinfo/heretic.txt b/wadsrc/static/mapinfo/heretic.txt
index af0295ef30..73310ad474 100644
--- a/wadsrc/static/mapinfo/heretic.txt
+++ b/wadsrc/static/mapinfo/heretic.txt
@@ -67,6 +67,7 @@ gameinfo
 	statscreen_coop = "CoopStatusScreen"
 	statscreen_dm = "DeathmatchStatusScreen"
 	statscreen_single = "RavenStatusScreen"
+	messageboxclass = "MessageBoxMenu"
 }
 
 DoomEdNums
diff --git a/wadsrc/static/mapinfo/hexen.txt b/wadsrc/static/mapinfo/hexen.txt
index 37afe73362..618fd4be74 100644
--- a/wadsrc/static/mapinfo/hexen.txt
+++ b/wadsrc/static/mapinfo/hexen.txt
@@ -65,6 +65,7 @@ gameinfo
 	statscreen_coop = "CoopStatusScreen"
 	statscreen_dm = "DeathmatchStatusScreen"
 	statscreen_single = "RavenStatusScreen"
+	messageboxclass = "MessageBoxMenu"
 }
 
 DoomEdNums
diff --git a/wadsrc/static/mapinfo/mindefaults.txt b/wadsrc/static/mapinfo/mindefaults.txt
index 8855872811..26ab0d9395 100644
--- a/wadsrc/static/mapinfo/mindefaults.txt
+++ b/wadsrc/static/mapinfo/mindefaults.txt
@@ -53,6 +53,7 @@ gameinfo
 	statscreen_mapnamefont = "BigFont"
 	statscreen_finishedpatch = "WIF"
 	statscreen_enteringpatch = "WIENTER"
+	messageboxclass = "MessageBoxMenu"
 }
 
 DoomEdNums
diff --git a/wadsrc/static/mapinfo/strife.txt b/wadsrc/static/mapinfo/strife.txt
index 419c8c13ff..0b52b213e4 100644
--- a/wadsrc/static/mapinfo/strife.txt
+++ b/wadsrc/static/mapinfo/strife.txt
@@ -67,6 +67,7 @@ gameinfo
 	statscreen_dm = "DeathmatchStatusScreen"
 	statscreen_single = "RavenStatusScreen"
 	statusbarclass = "StrifeStatusBar"
+	messageboxclass = "MessageBoxMenu"
 }
 
 DoomEdNums
diff --git a/wadsrc/static/zscript/menu/messagebox.txt b/wadsrc/static/zscript/menu/messagebox.txt
index 48d9949a39..86796d3011 100644
--- a/wadsrc/static/zscript/menu/messagebox.txt
+++ b/wadsrc/static/zscript/menu/messagebox.txt
@@ -50,7 +50,7 @@ class MessageBoxMenu : Menu
 	//
 	//=============================================================================
 
-	void Init(Menu parent, String message, int messagemode, bool playsound = false, Name cmd = 'None', voidptr native_handler = null)
+	virtual void Init(Menu parent, String message, int messagemode, bool playsound = false, Name cmd = 'None', voidptr native_handler = null)
 	{
 		Super.Init(parent);
 		mAction = cmd;