diff --git a/src/gamedata/a_weapons.h b/src/gamedata/a_weapons.h
index 82cfd2999d..786990223f 100644
--- a/src/gamedata/a_weapons.h
+++ b/src/gamedata/a_weapons.h
@@ -154,9 +154,9 @@ enum
 	WIF_STAFF2_KICKBACK =	0x00002000, // the powered-up Heretic staff has special kickback
 	WIF_NOAUTOAIM =			0x00004000, // this weapon never uses autoaim (useful for ballistic projectiles)
 	WIF_MELEEWEAPON =		0x00008000,	// melee weapon. Used by bots and monster AI.
-	//WIF_DEHAMMO	=			0x00010000,	
-	WIF_NODEATHDESELECT =	0x00020000, // Don't jump to the Deselect state when the player dies
-	WIF_NODEATHINPUT =		0x00040000, // The weapon cannot be fired/reloaded/whatever when the player is dead
-	WIF_CHEATNOTWEAPON	=	0x08000000,	// Give cheat considers this not a weapon (used by Sigil)
+	WIF_NODEATHDESELECT =	0x00010000, // Don't jump to the Deselect state when the player dies
+	WIF_NODEATHINPUT =		0x00020000, // The weapon cannot be fired/reloaded/whatever when the player is dead
+	WIF_CHEATNOTWEAPON	=	0x00040000,	// Give cheat considers this not a weapon (used by Sigil)
+	WIF_NOAUTOSWITCHTO =	0x00080000, // cannot be switched to when autoswitching weapons.
 };
 
diff --git a/src/gamedata/d_dehacked.cpp b/src/gamedata/d_dehacked.cpp
index 6ab56ebd65..28ac9b801f 100644
--- a/src/gamedata/d_dehacked.cpp
+++ b/src/gamedata/d_dehacked.cpp
@@ -1718,6 +1718,21 @@ static int PatchAmmo (int ammoNum)
 	return result;
 }
 
+struct DehWeaponBits
+{
+	const char* name;
+	int value;
+};
+
+DehWeaponBits wbits[] = {
+	{ "NOTHRUST", -1 },	// i.e. set kickback to 0
+	{ "SILENT", WIF_NOALERT },
+	{ "NOAUTOFIRE", WIF_NOAUTOFIRE },
+	{ "FLEEMELEE", WIF_MELEEWEAPON },
+	{ "AUTOSWITCHFROM", WIF_WIMPY_WEAPON },	// ugh, I wish I could change this stupid name...
+	{ "NOAUTOSWITCHTO", WIF_NOAUTOSWITCHTO }
+};
+
 static int PatchWeapon (int weapNum)
 {
 	int result;
@@ -1819,6 +1834,57 @@ static int PatchWeapon (int weapNum)
 		{
 			if (info) info->IntVar(NAME_MinSelAmmo1) = val;
 		}
+		else if (stricmp(Line1, "MBF21 Bits") == 0)
+		{
+			uint32_t value = 0;
+			bool vchanged = false;
+
+			char* strval;
+
+			for (strval = Line2; (strval = strtok(strval, ",+| \t\f\r")); strval = NULL)
+			{
+				if (IsNum(strval))
+				{
+					value |= (unsigned long)strtoll(strval, NULL, 10);
+					vchanged = true;
+				}
+				else
+				{
+					unsigned i;
+					for (i = 0; i < countof(wbits); i++)
+					{
+						if (!stricmp(strval, wbits[i].name))
+						{
+							vchanged = true;
+							value |= 1 << i;
+							break;
+						}
+					}
+					if (i == countof(wbits))
+					{
+						DPrintf(DMSG_ERROR, "Unknown bit mnemonic %s\n", strval);
+					}
+				}
+			}
+			if (vchanged)
+			{
+				int kickback = 100;
+				int flags = 0;
+				for (size_t i = 0; i < countof(wbits); i++)
+				{
+					if (value & (1 << i))
+					{
+						int val = wbits[i].value;
+						if (val == -1) kickback = 0;
+						else flags |= wbits[i].value;
+					}
+				}
+				info->IntVar(NAME_Kickback) = kickback;
+				info->IntVar(NAME_WeaponFlags) = flags;
+			}
+			DPrintf(DMSG_SPAMMY, "MBF21 Bits: %d (0x%08x)\n", info->flags.GetValue(), info->flags.GetValue());
+		}
+
 		else
 		{
 			Printf (unknown_str, Line1, "Weapon", weapNum);
diff --git a/wadsrc/static/zscript/actors/doom/weaponchainsaw.zs b/wadsrc/static/zscript/actors/doom/weaponchainsaw.zs
index e4f3cc6c16..d3b6932d1d 100644
--- a/wadsrc/static/zscript/actors/doom/weaponchainsaw.zs
+++ b/wadsrc/static/zscript/actors/doom/weaponchainsaw.zs
@@ -16,6 +16,7 @@ class Chainsaw : Weapon
 		Obituary "$OB_MPCHAINSAW";
 		Tag "$TAG_CHAINSAW";
 		+WEAPON.MELEEWEAPON		
+		+WEAPON.NOAUTOSWITCHTO
 	}
 	States
 	{
diff --git a/wadsrc/static/zscript/actors/doom/weaponfist.zs b/wadsrc/static/zscript/actors/doom/weaponfist.zs
index c27188773c..d02099bccf 100644
--- a/wadsrc/static/zscript/actors/doom/weaponfist.zs
+++ b/wadsrc/static/zscript/actors/doom/weaponfist.zs
@@ -14,6 +14,7 @@ class Fist : Weapon
 		Tag "$TAG_FIST";
 		+WEAPON.WIMPY_WEAPON
 		+WEAPON.MELEEWEAPON
+		+WEAPON.NOAUTOSWITCHTO
 	}
 	States
 	{
diff --git a/wadsrc/static/zscript/actors/player/player.zs b/wadsrc/static/zscript/actors/player/player.zs
index fbf2c24ca5..cbe6a5c3dd 100644
--- a/wadsrc/static/zscript/actors/player/player.zs
+++ b/wadsrc/static/zscript/actors/player/player.zs
@@ -333,7 +333,7 @@ class PlayerPawn : Actor
 			(player.ReadyWeapon == NULL || player.ReadyWeapon.bWimpy_Weapon))
 		{
 			let best = BestWeapon (ammotype);
-			if (best != NULL && (player.ReadyWeapon == NULL ||
+			if (best != NULL && && !best.bNoAutoSwitchTo && (player.ReadyWeapon == NULL ||
 				best.SelectionOrder < player.ReadyWeapon.SelectionOrder))
 			{
 				player.PendingWeapon = best;