diff --git a/src/g_inventory/a_weapons.cpp b/src/g_inventory/a_weapons.cpp
index 86819f75e..94e65a33c 100644
--- a/src/g_inventory/a_weapons.cpp
+++ b/src/g_inventory/a_weapons.cpp
@@ -55,7 +55,6 @@ IMPLEMENT_POINTERS_START(AWeapon)
 	IMPLEMENT_POINTER(SisterWeapon)
 IMPLEMENT_POINTERS_END
 
-/*
 DEFINE_FIELD(AWeapon, AmmoType1)
 DEFINE_FIELD(AWeapon, AmmoType2)	
 DEFINE_FIELD(AWeapon, AmmoGive1)
@@ -86,7 +85,6 @@ DEFINE_FIELD(AWeapon, GivenAsMorphWeapon)
 DEFINE_FIELD(AWeapon, bAltFire)
 DEFINE_FIELD(AWeapon, WeaponFlags)
 DEFINE_FIELD(AWeapon, bDehAmmo)
-*/
 
 //===========================================================================
 //
diff --git a/src/p_mobj.cpp b/src/p_mobj.cpp
index 5e555e1db..1fd612acf 100644
--- a/src/p_mobj.cpp
+++ b/src/p_mobj.cpp
@@ -7284,7 +7284,7 @@ AActor *P_SpawnPlayerMissile (AActor *source, double x, double y, double z,
 	DAngle vrange = nofreeaim ? 35. : 0.;
 
 	if (!pLineTarget) pLineTarget = &scratch;
-	if (!(flags & ALF_NOWEAPONCHECK) && source->player && source->player->ReadyWeapon && ((source->player->ReadyWeapon->IntVar(NAME_WeaponFlags) & WIF_NOAUTOAIM) || noautoaim))
+	if (!(aimflags & ALF_NOWEAPONCHECK) && source->player && source->player->ReadyWeapon && ((source->player->ReadyWeapon->IntVar(NAME_WeaponFlags) & WIF_NOAUTOAIM) || noautoaim))
 	{
 		// Keep exactly the same angle and pitch as the player's own aim
 		an = angle;
diff --git a/src/sc_man_scanner.re b/src/sc_man_scanner.re
index 3ef66b760..c4fcf6399 100644
--- a/src/sc_man_scanner.re
+++ b/src/sc_man_scanner.re
@@ -179,6 +179,7 @@ std2:
 		'none'						{ RET(TK_None); }
 		'auto'						{ RET(TK_Auto); }
 		'property'					{ RET(TK_Property); }
+		'flagdef'					{ RET(ParseVersion >= MakeVersion(3, 7, 0)? TK_FlagDef : TK_Identifier); }
 		'native'					{ RET(TK_Native); }
 		'var'						{ RET(TK_Var); }
 		'out'						{ RET(ParseVersion >= MakeVersion(1, 0, 0)? TK_Out : TK_Identifier); }
diff --git a/src/sc_man_tokens.h b/src/sc_man_tokens.h
index dfe49518a..82dac84d8 100644
--- a/src/sc_man_tokens.h
+++ b/src/sc_man_tokens.h
@@ -67,6 +67,7 @@ xx(TK_Long,					"'long'")
 xx(TK_ULong,				"'ulong'")
 xx(TK_Void,					"'void'")
 xx(TK_Struct,				"'struct'")
+xx(TK_FlagDef,				"'flagdef'")
 xx(TK_Property,				"'property'")
 xx(TK_Class,				"'class'")
 xx(TK_Enum,					"'enum'")
diff --git a/src/scripting/symbols.cpp b/src/scripting/symbols.cpp
index 335edd552..fbb06e900 100644
--- a/src/scripting/symbols.cpp
+++ b/src/scripting/symbols.cpp
@@ -196,6 +196,29 @@ PProperty::PProperty(FName name, TArray<PField *> &fields)
 	Variables = std::move(fields);
 }
 
+/* PProperty *****************************************************************/
+
+IMPLEMENT_CLASS(PPropFlag, false, false)
+
+//==========================================================================
+//
+// PField - Default Constructor
+//
+//==========================================================================
+
+PPropFlag::PPropFlag()
+	: PSymbol(NAME_None)
+{
+}
+
+PPropFlag::PPropFlag(FName name, PField * field, int bitValue, bool forDecorate)
+	: PSymbol(name)
+{
+	Offset = field;
+	bitval = bitValue;
+	decorateOnly = forDecorate;
+}
+
 //==========================================================================
 //
 //
diff --git a/src/scripting/symbols.h b/src/scripting/symbols.h
index bc6de46b6..954edc85a 100644
--- a/src/scripting/symbols.h
+++ b/src/scripting/symbols.h
@@ -109,10 +109,11 @@ class PPropFlag : public PSymbol
 {
 	DECLARE_CLASS(PPropFlag, PSymbol);
 public:
-	PPropFlag(FName name, PField *offset, int bitval);
+	PPropFlag(FName name, PField *offset, int bitval, bool decorateonly);
 
 	PField *Offset;
 	int bitval;
+	bool decorateOnly;
 
 protected:
 	PPropFlag();
diff --git a/src/scripting/thingdef_data.cpp b/src/scripting/thingdef_data.cpp
index c88262298..575a689c3 100644
--- a/src/scripting/thingdef_data.cpp
+++ b/src/scripting/thingdef_data.cpp
@@ -445,30 +445,10 @@ static FFlagDef InventoryFlagDefs[] =
 static FFlagDef WeaponFlagDefs[] =
 {
 	// Weapon flags
-	DEFINE_FLAG(WIF, NOAUTOFIRE, AWeapon, WeaponFlags),
-	DEFINE_FLAG(WIF, READYSNDHALF, AWeapon, WeaponFlags),
-	DEFINE_FLAG(WIF, DONTBOB, AWeapon, WeaponFlags),
-	DEFINE_FLAG(WIF, AXEBLOOD, AWeapon, WeaponFlags),
-	DEFINE_FLAG(WIF, NOALERT, AWeapon, WeaponFlags),
-	DEFINE_FLAG(WIF, AMMO_OPTIONAL, AWeapon, WeaponFlags),
-	DEFINE_FLAG(WIF, ALT_AMMO_OPTIONAL, AWeapon, WeaponFlags),
-	DEFINE_FLAG(WIF, PRIMARY_USES_BOTH, AWeapon, WeaponFlags),
-	DEFINE_FLAG(WIF, WIMPY_WEAPON, AWeapon, WeaponFlags),
-	DEFINE_FLAG(WIF, POWERED_UP, AWeapon, WeaponFlags),
-	DEFINE_FLAG(WIF, STAFF2_KICKBACK, AWeapon, WeaponFlags),
-	DEFINE_FLAG(WIF, MELEEWEAPON, AWeapon, WeaponFlags),
-	DEFINE_FLAG(WIF, CHEATNOTWEAPON, AWeapon, WeaponFlags),
-	DEFINE_FLAG(WIF, NO_AUTO_SWITCH, AWeapon, WeaponFlags),
-	DEFINE_FLAG(WIF, AMMO_CHECKBOTH, AWeapon, WeaponFlags),
-	DEFINE_FLAG(WIF, NOAUTOAIM, AWeapon, WeaponFlags),
-	DEFINE_FLAG(WIF, NODEATHDESELECT, AWeapon, WeaponFlags),
-	DEFINE_FLAG(WIF, NODEATHINPUT, AWeapon, WeaponFlags),
-	DEFINE_FLAG(WIF, ALT_USES_BOTH, AWeapon, WeaponFlags),
-
 	DEFINE_DUMMY_FLAG(NOLMS, false),
 	DEFINE_DUMMY_FLAG(ALLOW_WITH_RESPAWN_INVUL, false),
-	DEFINE_DUMMY_FLAG(BFG, true),
-	DEFINE_DUMMY_FLAG(EXPLOSIVE, true),
+	DEFINE_DUMMY_FLAG(BFG, false),
+	DEFINE_DUMMY_FLAG(EXPLOSIVE, false),
 };
 
 
@@ -511,6 +491,8 @@ static const struct FFlagList { const PClass * const *Type; FFlagDef *Defs; int
 };
 #define NUM_FLAG_LISTS (countof(FlagLists))
 
+static FFlagDef forInternalFlags;
+
 //==========================================================================
 //
 // Find a flag by name using a binary search
@@ -548,6 +530,47 @@ static FFlagDef *FindFlag (FFlagDef *flags, int numflags, const char *flag)
 
 FFlagDef *FindFlag (const PClass *type, const char *part1, const char *part2, bool strict)
 {
+
+	if (part2 == nullptr)
+	{
+		FStringf internalname("@flagdef@%s", part1);
+		FName name(internalname, true);
+		if (name != NAME_None)
+		{
+			auto field = dyn_cast<PPropFlag>(type->FindSymbol(name, true));
+			if (field != nullptr && (!strict || !field->decorateOnly))
+			{
+				forInternalFlags.fieldsize = 4;
+				forInternalFlags.name = "";
+				forInternalFlags.flagbit = 1 << field->bitval;
+				forInternalFlags.structoffset = field->Offset->Offset;
+				forInternalFlags.varflags = 0;
+				return &forInternalFlags;
+			}
+		}
+	}
+	else
+	{
+		FStringf internalname("@flagdef@%s.%s", part1, part2);
+		FName name(internalname, true);
+		if (name != NAME_None)
+		{
+			auto field = dyn_cast<PPropFlag>(type->FindSymbol(name, true));
+			if (field != nullptr)
+			{
+				forInternalFlags.fieldsize = 4;
+				forInternalFlags.name = "";
+				forInternalFlags.flagbit = 1 << field->bitval;
+				forInternalFlags.structoffset = field->Offset->Offset;
+				forInternalFlags.varflags = 0;
+				return &forInternalFlags;
+			}
+		}
+	}
+
+	// Not found. Try the internal flag definitions.
+
+
 	FFlagDef *def;
 
 	if (part2 == NULL)
diff --git a/src/scripting/zscript/ast.cpp b/src/scripting/zscript/ast.cpp
index 773173503..99453901d 100644
--- a/src/scripting/zscript/ast.cpp
+++ b/src/scripting/zscript/ast.cpp
@@ -348,6 +348,17 @@ static void PrintProperty(FLispString &out, ZCC_TreeNode *node)
 	out.Close();
 }
 
+static void PrintFlagDef(FLispString &out, ZCC_TreeNode *node)
+{
+	ZCC_FlagDef *snode = (ZCC_FlagDef *)node;
+	out.Break();
+	out.Open("flagdef");
+	out.AddName(snode->NodeName);
+	out.AddName(snode->RefName);
+	out.AddInt(snode->BitValue);
+	out.Close();
+}
+
 static void PrintStaticArrayState(FLispString &out, ZCC_TreeNode *node)
 {
 	auto *snode = (ZCC_StaticArrayStatement *)node;
@@ -959,6 +970,7 @@ void (* const TreeNodePrinter[NUM_AST_NODE_TYPES])(FLispString &, ZCC_TreeNode *
 	PrintExprClassCast,
 	PrintStaticArrayState,
 	PrintProperty,
+	PrintFlagDef,
 };
 
 FString ZCC_PrintAST(ZCC_TreeNode *root)
diff --git a/src/scripting/zscript/zcc-parse.lemon b/src/scripting/zscript/zcc-parse.lemon
index 97b63198a..83da14100 100644
--- a/src/scripting/zscript/zcc-parse.lemon
+++ b/src/scripting/zscript/zcc-parse.lemon
@@ -313,6 +313,7 @@ class_innards(X) ::= .									{ X = NULL; }
 class_innards(X) ::= class_innards(X) class_member(B).	{ SAFE_APPEND(X,B); }
 
 %type property_def{ZCC_Property *}
+%type flag_def{ZCC_FlagDef *}
 %type struct_def{ZCC_Struct *}
 %type enum_def {ZCC_Enum *}
 %type states_def {ZCC_States *}
@@ -325,6 +326,7 @@ class_member(X) ::= states_def(A).						{ X = A; /*X-overwrites-A*/ }
 class_member(X) ::= default_def(A).						{ X = A; /*X-overwrites-A*/ }
 class_member(X) ::= const_def(A).						{ X = A; /*X-overwrites-A*/ }
 class_member(X) ::= property_def(A).					{ X = A; /*X-overwrites-A*/ }
+class_member(X) ::= flag_def(A).						{ X = A; /*X-overwrites-A*/ }
 class_member(X) ::= staticarray_statement(A).			{ X = A; /*X-overwrites-A*/ }
 
 
@@ -344,6 +346,16 @@ property_def(X) ::= PROPERTY(T) IDENTIFIER(A) COLON identifier_list(B) SEMICOLON
 	X = def;
 }
 
+flag_def(X) ::= FLAGDEF(T) IDENTIFIER(A) COLON IDENTIFIER(B) COMMA INTCONST(C) SEMICOLON.
+{
+	NEW_AST_NODE(FlagDef,def,T);
+	def->NodeName = A.Name();
+	def->RefName = B.Name();
+	def->BitValue = C.Int;
+	X = def;
+}
+
+
 identifier_list(X) ::= IDENTIFIER(A).
 {
 	NEW_AST_NODE(Identifier,id,A);
diff --git a/src/scripting/zscript/zcc_compile.cpp b/src/scripting/zscript/zcc_compile.cpp
index ab31ee05f..ae36d3589 100644
--- a/src/scripting/zscript/zcc_compile.cpp
+++ b/src/scripting/zscript/zcc_compile.cpp
@@ -175,6 +175,10 @@ void ZCCCompiler::ProcessClass(ZCC_Class *cnode, PSymbolTreeNode *treenode)
 			cls->Properties.Push(static_cast<ZCC_Property *>(node));
 			break;
 
+		case AST_FlagDef:
+			cls->FlagDefs.Push(static_cast<ZCC_FlagDef*>(node));
+			break;
+
 		case AST_VarDeclarator: 
 			cls->Fields.Push(static_cast<ZCC_VarDeclarator *>(node)); 
 			break;
@@ -1375,6 +1379,10 @@ void ZCCCompiler::CompileAllProperties()
 	{
 		if (c->Properties.Size() > 0)
 			CompileProperties(c->ClassType(), c->Properties, c->Type()->TypeName);
+
+		if (c->FlagDefs.Size() > 0)
+			CompileFlagDefs(c->ClassType(), c->FlagDefs, c->Type()->TypeName);
+
 	}
 }
 
@@ -1415,20 +1423,83 @@ bool ZCCCompiler::CompileProperties(PClass *type, TArray<ZCC_Property *> &Proper
 				fields.Push(f);
 				id = (ZCC_Identifier*)id->SiblingNext;
 			} while (id != p->Body);
+
+			FString qualifiedname;
+			// Store the full qualified name and prepend some 'garbage' to the name so that no conflicts with other symbol types can happen.
+			// All these will be removed from the symbol table after the compiler finishes to free up the allocated space.
+			FName name = FName(p->NodeName);
+			if (prefix == NAME_None) qualifiedname.Format("@property@%s", name.GetChars());
+			else qualifiedname.Format("@property@%s.%s", prefix.GetChars(), name.GetChars());
+
+			fields.ShrinkToFit();
+			if (!type->VMType->Symbols.AddSymbol(Create<PProperty>(qualifiedname, fields)))
+			{
+				Error(id, "Unable to add property %s to class %s", FName(p->NodeName).GetChars(), type->TypeName.GetChars());
+			}
 		}
+	}
+	return true;
+}
 
-		FString qualifiedname;
-		// Store the full qualified name and prepend some 'garbage' to the name so that no conflicts with other symbol types can happen.
-		// All these will be removed from the symbol table after the compiler finishes to free up the allocated space.
-		FName name = FName(p->NodeName);
-		if (prefix == NAME_None) qualifiedname.Format("@property@%s", name.GetChars());
-		else qualifiedname.Format("@property@%s.%s", prefix.GetChars(), name.GetChars());
+//==========================================================================
+//
+// ZCCCompiler :: CompileProperties
+//
+// builds the internal structure of a single class or struct
+//
+//==========================================================================
 
-		fields.ShrinkToFit();
-		if (!type->VMType->Symbols.AddSymbol(Create<PProperty>(qualifiedname, fields)))
+bool ZCCCompiler::CompileFlagDefs(PClass *type, TArray<ZCC_FlagDef *> &Properties, FName prefix)
+{
+	if (!type->IsDescendantOf(RUNTIME_CLASS(AActor)))
+	{
+		Error(Properties[0], "Flags can only be defined for actors");
+		return false;
+	}
+	for (auto p : Properties)
+	{
+		PField *field;
+		FName referenced = FName(p->RefName);
+
+		if (FName(p->NodeName) == FName("prefix") && Wads.GetLumpFile(Lump) == 0)
 		{
-			Error(id, "Unable to add property %s to class %s", FName(p->NodeName).GetChars(), type->TypeName.GetChars());
+			// only for internal definitions: Allow setting a prefix. This is only for compatiblity with the old DECORATE property parser, but not for general use.
+			prefix = referenced;
 		}
+		else
+		{
+			field = dyn_cast<PField>(type->FindSymbol(referenced, true));
+			if (field == nullptr)
+			{
+				Error(p, "Variable %s not found in %s", referenced.GetChars(), type->TypeName.GetChars());
+			}
+			if (!field->Type->isInt() || field->Type->Size != 4)
+			{
+				Error(p, "Variable %s in %s must have a size of 4 bytes for use as flag storage", referenced.GetChars(), type->TypeName.GetChars());
+			}
+
+
+			FString qualifiedname;
+			// Store the full qualified name and prepend some 'garbage' to the name so that no conflicts with other symbol types can happen.
+			// All these will be removed from the symbol table after the compiler finishes to free up the allocated space.
+			FName name = FName(p->NodeName);
+			for (int i = 0; i < 2; i++)
+			{
+				if (i == 0) qualifiedname.Format("@flagdef@%s", name.GetChars());
+				else
+				{
+					if (prefix == NAME_None) continue;
+					qualifiedname.Format("@flagdef@%s.%s", prefix.GetChars(), name.GetChars());
+				}
+
+				if (!type->VMType->Symbols.AddSymbol(Create<PPropFlag>(qualifiedname, field, p->BitValue, i == 0 && prefix != NAME_None)))
+				{
+					Error(p, "Unable to add flag definition %s to class %s", FName(p->NodeName).GetChars(), type->TypeName.GetChars());
+				}
+			}
+
+			type->VMType->AddNativeField(FStringf("b%s", name.GetChars()), TypeSInt32, field->Offset, 0, 1 << p->BitValue);
+		} 
 	}
 	return true;
 }
diff --git a/src/scripting/zscript/zcc_compile.h b/src/scripting/zscript/zcc_compile.h
index 9a4a0af8b..238b5431c 100644
--- a/src/scripting/zscript/zcc_compile.h
+++ b/src/scripting/zscript/zcc_compile.h
@@ -54,6 +54,7 @@ struct ZCC_ClassWork : public ZCC_StructWork
 	TArray<ZCC_Default *> Defaults;
 	TArray<ZCC_States *> States;
 	TArray<ZCC_Property *> Properties;
+	TArray<ZCC_FlagDef *> FlagDefs;
 
 	ZCC_ClassWork(ZCC_Class * s, PSymbolTreeNode *n)
 	{
@@ -110,6 +111,7 @@ private:
 	bool CompileFields(PContainerType *type, TArray<ZCC_VarDeclarator *> &Fields, PClass *Outer, PSymbolTable *TreeNodes, bool forstruct, bool hasnativechildren = false);
 	void CompileAllProperties();
 	bool CompileProperties(PClass *type, TArray<ZCC_Property *> &Properties, FName prefix);
+	bool CompileFlagDefs(PClass *type, TArray<ZCC_FlagDef *> &FlagDefs, FName prefix);
 	FString FlagsToString(uint32_t flags);
 	PType *DetermineType(PType *outertype, ZCC_TreeNode *field, FName name, ZCC_Type *ztype, bool allowarraytypes, bool formember);
 	PType *ResolveArraySize(PType *baseType, ZCC_Expression *arraysize, PContainerType *cls);
diff --git a/src/scripting/zscript/zcc_parser.cpp b/src/scripting/zscript/zcc_parser.cpp
index 9093b7b51..fde8e1f3f 100644
--- a/src/scripting/zscript/zcc_parser.cpp
+++ b/src/scripting/zscript/zcc_parser.cpp
@@ -150,6 +150,7 @@ static void InitTokenMap()
 	TOKENDEF ('}',				ZCC_RBRACE);
 	TOKENDEF (TK_Struct,		ZCC_STRUCT);
 	TOKENDEF (TK_Property,		ZCC_PROPERTY);
+	TOKENDEF (TK_FlagDef,		ZCC_FLAGDEF);
 	TOKENDEF (TK_Transient,		ZCC_TRANSIENT);
 	TOKENDEF (TK_Enum,			ZCC_ENUM);
 	TOKENDEF2(TK_SByte,			ZCC_SBYTE,		NAME_sByte);
diff --git a/src/scripting/zscript/zcc_parser.h b/src/scripting/zscript/zcc_parser.h
index 1089b2ed8..272d7e141 100644
--- a/src/scripting/zscript/zcc_parser.h
+++ b/src/scripting/zscript/zcc_parser.h
@@ -134,6 +134,7 @@ enum EZCCTreeNodeType
 	AST_ClassCast,
 	AST_StaticArrayStatement,
 	AST_Property,
+	AST_FlagDef,
 
 	NUM_AST_NODE_TYPES
 };
@@ -226,6 +227,12 @@ struct ZCC_Property : ZCC_NamedNode
 	ZCC_TreeNode *Body;
 };
 
+struct ZCC_FlagDef : ZCC_NamedNode
+{
+	ENamedName RefName;
+	int BitValue;
+};
+
 struct ZCC_Class : ZCC_Struct
 {
 	ZCC_Identifier *ParentName;
diff --git a/wadsrc/static/zscript/inventory/weapons.txt b/wadsrc/static/zscript/inventory/weapons.txt
index e98dba8e8..58b2a071d 100644
--- a/wadsrc/static/zscript/inventory/weapons.txt
+++ b/wadsrc/static/zscript/inventory/weapons.txt
@@ -59,6 +59,26 @@ class Weapon : StateProvider native
 	property SlotNumber: SlotNumber;
 	property SlotPriority: SlotPriority;
 
+	flagdef NoAutoFire: WeaponFlags, 0;			// weapon does not autofire
+	flagdef ReadySndHalf: WeaponFlags, 1;		// ready sound is played ~1/2 the time
+	flagdef DontBob: WeaponFlags, 2;			// don't bob the weapon
+	flagdef AxeBlood: WeaponFlags, 3;			// weapon makes axe blood on impact
+	flagdef NoAlert: WeaponFlags, 4;			// weapon does not alert monsters
+	flagdef Ammo_Optional: WeaponFlags, 5;		// weapon can use ammo but does not require it
+	flagdef Alt_Ammo_Optional: WeaponFlags, 6;	// alternate fire can use ammo but does not require it
+	flagdef Primary_Uses_Both: WeaponFlags, 7;	// primary fire uses both ammo
+	flagdef Alt_Uses_Both: WeaponFlags, 8;		// alternate fire uses both ammo
+	flagdef Wimpy_Weapon:WeaponFlags, 9;		// change away when ammo for another weapon is replenished
+	flagdef Powered_Up: WeaponFlags, 10;		// this is a tome-of-power'ed version of its sister
+	flagdef Ammo_CheckBoth: WeaponFlags, 11;	// check for both primary and secondary fire before switching it off
+	flagdef No_Auto_Switch: WeaponFlags, 12;	// never switch to this weapon when it's picked up
+	flagdef Staff2_Kickback: WeaponFlags, 13;	// the powered-up Heretic staff has special kickback
+	flagdef NoAutoaim: WeaponFlags, 14;			// this weapon never uses autoaim (useful for ballistic projectiles)
+	flagdef MeleeWeapon: WeaponFlags, 15;		// melee weapon. Used by monster AI with AVOIDMELEE.
+	flagdef NoDeathDeselect: WeaponFlags, 16;	// Don't jump to the Deselect state when the player dies
+	flagdef NoDeathInput: WeaponFlags, 17;		// The weapon cannot be fired/reloaded/whatever when the player is dead
+	flagdef CheatNotWeapon: WeaponFlags, 18;	// Give cheat considers this not a weapon (used by Sigil)
+
 	Default
 	{
 		Inventory.PickupSound "misc/w_pkup";