diff --git a/scripting.py b/scripting.py
index ee7c218..24392cc 100644
--- a/scripting.py
+++ b/scripting.py
@@ -39,7 +39,7 @@ class Botdef(TPrs):
 class Flagdef(TPrs):
     def InitPersistent(self, stName, value = True):
         self.stName = stName
-        self.value = True
+        self.value = value
 
 class Rbot(TPrs):
     def InitPersistent(self, botdef):
@@ -74,7 +74,7 @@ class Vm(TPrs):
         self.mpflagdef[flagdef] = fValue
 
     def FFlagSet(self, flagdef):
-        return self.mpflagdef[flagdef]
+        return self.mpflagdef[flagdef] if flagdef in self.mpflagdef else flagdef.value
     
     def AddPlayer(self):
         rgbotdefPlayer = [botdef for botdef in self.defs.rgbotdef if botdef.fPlayer]
@@ -116,6 +116,15 @@ class StypeEnum(Stype):
 class StypeStmt(StypeEnum):
     rgclsSynt = []
 
+class StypeNewFlag(Stype):
+    def RgsyntFromSt(self, defs, st):
+        if len(st) > 0:
+            for flagdef in defs.rgflagdef:
+                if flagdef.stName == st:
+                    return
+            yield SyntMakeFlagDef(defs, st, False)
+            yield SyntMakeFlagDef(defs, st, True)
+
 class Rtype(Stype):
     "Runtime type"
     def StForSobj(self, sobj):
@@ -179,6 +188,11 @@ class Synt(Typeable):
     def SyntDefault(cls):
         return cls()
 
+    def WithParent(self, syntParent):
+        assert self.syntParent == None
+        self.syntParent = syntParent
+        return self
+
     def Populate(self):
         "Populate rgsynt with useful default values."
         pass
@@ -220,9 +234,7 @@ class Synt(Typeable):
                 pcur.pwTooltip.AddTip(pwTypein, Tooltip)
 
     def Replace(self, syntOld, syntNew):
-        assert syntNew.syntParent == None
-        syntNew.syntParent = self
-        self.rgsynt[self.Isynt(syntOld)] = syntNew
+        self.rgsynt[self.Isynt(syntOld)] = syntNew.WithParent(self)
 
     def Append(self, syntNew):
         assert syntNew.syntParent == None
@@ -404,6 +416,21 @@ class SyntFlagRef(Synt):
         except:
             return env.vm.Fail("No such flag", self)
 
+class SyntMakeFlagDef(Synt):
+    def InitPersistent(self, defs, stName, fInit):
+        Synt.InitPersistent(self)
+        self.defs = defs
+        self.stName = stName
+        self.fInit = fInit
+
+    def StForTypein(self):
+        return "New flag: " + self.stName + " (initially " + str(self.fInit) + ")"
+    
+    def WithParent(self, syntParent):
+        flagdef = Flagdef(self.stName, self.fInit)
+        self.defs.rgflagdef.append(flagdef)
+        return SyntFlagRef(flagdef).WithParent(syntParent)
+
 class SyntIsFlagSet(SyntDesc):
     desc = [["set"]]
     def Eval(self, env, val):
@@ -441,7 +468,7 @@ class SyntIf(SyntDesc):
 
 @RegStmt
 class SyntSet(SyntDesc):
-    desc = [["Set flag"], " ", RtypeFlag(), " to ", RtypeUnion(RtypeBool(), RtypeFlag())]
+    desc = [["Set flag"], " ", RtypeUnion(RtypeFlag(), StypeNewFlag()), " to ", RtypeUnion(RtypeBool(), RtypeFlag())]
     lvalue = SyntDesc.DefProp(0)
     expr = SyntDesc.DefProp(1)
     def Eval(self, env):