diff --git a/compiler/src/prog8/compiler/astprocessing/BoolRemover.kt b/compiler/src/prog8/compiler/astprocessing/BoolRemover.kt
index 30df7e7b5..a85ca8019 100644
--- a/compiler/src/prog8/compiler/astprocessing/BoolRemover.kt
+++ b/compiler/src/prog8/compiler/astprocessing/BoolRemover.kt
@@ -2,6 +2,7 @@ package prog8.compiler.astprocessing
 
 import prog8.ast.Node
 import prog8.ast.Program
+import prog8.ast.base.FatalAstException
 import prog8.ast.expressions.*
 import prog8.ast.statements.Subroutine
 import prog8.ast.statements.SubroutineParameter
@@ -14,7 +15,8 @@ internal class BoolRemover(val program: Program) : AstWalker() {
 
     override fun before(typecast: TypecastExpression, parent: Node): Iterable<IAstModification> {
         if(typecast.type == DataType.BOOL) {
-            val notZero = BinaryExpression(typecast.expression, "!=", NumericLiteral(DataType.UBYTE, 0.0, typecast.position), typecast.position)
+            val valueDt = typecast.expression.inferType(program).getOrElse { throw FatalAstException("unknown dt") }
+            val notZero = BinaryExpression(typecast.expression, "!=", NumericLiteral(valueDt, 0.0, typecast.position), typecast.position)
             return listOf(IAstModification.ReplaceNode(typecast, notZero, parent))
         }
         return noModifications
diff --git a/docs/source/todo.rst b/docs/source/todo.rst
index 5819f2aa1..bb39f23f1 100644
--- a/docs/source/todo.rst
+++ b/docs/source/todo.rst
@@ -3,10 +3,11 @@ TODO
 
 For next release
 ^^^^^^^^^^^^^^^^
-- make sure bool value is always 0 or 1 (all casts should convert), then:
-    - rewrite bool=bool^1 into bool=not bool
+- make sure bool value is always 0 or 1 (all casts should convert, or actually, bool!=0 comparison should return 0 or 1), then:
+    - ast rewrite bool=bool^1 into bool=not bool
     - should solve: bool bb = not bb -> larger code than bool bb ^= 1
 
+- check that bool==0 / bool==1 / bool!=0 / bool != 1  are optimized away
 
 ...