diff --git a/codeOptimizers/src/prog8/optimizer/UnusedCodeRemover.kt b/codeOptimizers/src/prog8/optimizer/UnusedCodeRemover.kt
index d42dadf84..10c301681 100644
--- a/codeOptimizers/src/prog8/optimizer/UnusedCodeRemover.kt
+++ b/codeOptimizers/src/prog8/optimizer/UnusedCodeRemover.kt
@@ -157,6 +157,12 @@ class UnusedCodeRemover(private val program: Program,
         return noModifications
     }
 
+    override fun after(assignment: Assignment, parent: Node): Iterable<IAstModification> {
+        if(assignment.target isSameAs assignment.value)
+            return listOf(IAstModification.Remove(assignment, parent as IStatementContainer))
+        return noModifications
+    }
+
     private fun deduplicateAssignments(statements: List<Statement>, scope: IStatementContainer): List<IAstModification> {
         // removes 'duplicate' assignments that assign the same target directly after another, unless it is a function call
         val linesToRemove = mutableListOf<Assignment>()
diff --git a/compiler/src/prog8/compiler/astprocessing/AstChecker.kt b/compiler/src/prog8/compiler/astprocessing/AstChecker.kt
index b30cc5845..e958ffe45 100644
--- a/compiler/src/prog8/compiler/astprocessing/AstChecker.kt
+++ b/compiler/src/prog8/compiler/astprocessing/AstChecker.kt
@@ -481,7 +481,9 @@ internal class AstChecker(private val program: Program,
                         errors.err("target datatype is unknown", assignment.target.position)
                     // otherwise, another error about missing symbol is already reported.
                 } else {
-                    errors.err("type of value $valueDt doesn't match target $targetDt", assignment.value.position)
+                    // allow bitwise operations on different types as long as the size is the same
+                    if (!((assignment.value as? BinaryExpression)?.operator in BitwiseOperators && targetDt.isBytes && valueDt.isBytes || targetDt.isWords && valueDt.isWords))
+                        errors.err("type of value $valueDt doesn't match target $targetDt", assignment.value.position)
                 }
             }
         }
@@ -1608,8 +1610,11 @@ internal class AstChecker(private val program: Program,
         else if(sourceDatatype== DataType.FLOAT && targetDatatype in IntegerDatatypes)
             errors.err("cannot assign float to ${targetDatatype.name.lowercase()}; possible loss of precision. Suggestion: round the value or revert to integer arithmetic", position)
         else {
-            if(targetDatatype!=DataType.UWORD && sourceDatatype !in PassByReferenceDatatypes)
-                errors.err("type of value $sourceDatatype doesn't match target $targetDatatype", position)
+            if(targetDatatype!=DataType.UWORD && sourceDatatype !in PassByReferenceDatatypes) {
+                // allow bitwise operations on different types as long as the size is the same
+                if (!((sourceValue as? BinaryExpression)?.operator in BitwiseOperators && targetDatatype.equalsSize(sourceDatatype)))
+                    errors.err("type of value $sourceDatatype doesn't match target $targetDatatype", position)
+            }
         }
 
         return false
diff --git a/compiler/src/prog8/compiler/astprocessing/BeforeAsmAstChanger.kt b/compiler/src/prog8/compiler/astprocessing/BeforeAsmAstChanger.kt
index e1a986b40..d4369edce 100644
--- a/compiler/src/prog8/compiler/astprocessing/BeforeAsmAstChanger.kt
+++ b/compiler/src/prog8/compiler/astprocessing/BeforeAsmAstChanger.kt
@@ -93,6 +93,11 @@ internal class BeforeAsmAstChanger(val program: Program,
                             )
                         }
                     } else {
+                        if(binExpr.left isSameAs assignment.target)
+                            return noModifications
+                        val typeCast = binExpr.left as? TypecastExpression
+                        if(typeCast!=null && typeCast.expression isSameAs assignment.target)
+                            return noModifications
                         val sourceDt = binExpr.left.inferType(program).getOrElse { throw AssemblyError("unknown dt") }
                         val (_, left) = binExpr.left.typecastTo(assignment.target.inferType(program).getOrElse { throw AssemblyError(
                             "unknown dt"
diff --git a/compiler/src/prog8/compiler/astprocessing/TypecastsAdder.kt b/compiler/src/prog8/compiler/astprocessing/TypecastsAdder.kt
index af6f6c8e7..3e5f2dd2d 100644
--- a/compiler/src/prog8/compiler/astprocessing/TypecastsAdder.kt
+++ b/compiler/src/prog8/compiler/astprocessing/TypecastsAdder.kt
@@ -133,9 +133,16 @@ class TypecastsAdder(val program: Program, val options: CompilationOptions, val
                         return listOf(IAstModification.ReplaceNode(expr.left, cast, expr))
                     }
                     if(leftDt istype DataType.WORD && rightDt.oneOf(DataType.UBYTE, DataType.UWORD)) {
-                        // cast left to unsigned
-                        val cast = TypecastExpression(expr.left, rightDt.getOr(DataType.UNDEFINED), true, expr.left.position)
-                        return listOf(IAstModification.ReplaceNode(expr.left, cast, expr))
+                        // cast left to unsigned word. Cast right to unsigned word if it is ubyte
+                        val mods = mutableListOf<IAstModification>()
+                        val cast = TypecastExpression(expr.left, DataType.UWORD, true, expr.left.position)
+                        mods += IAstModification.ReplaceNode(expr.left, cast, expr)
+                        if(rightDt istype DataType.UBYTE) {
+                            mods += IAstModification.ReplaceNode(expr.right,
+                                TypecastExpression(expr.right, DataType.UWORD, true, expr.right.position),
+                                expr)
+                        }
+                        return mods
                     }
                     if(rightDt istype DataType.BYTE && leftDt.oneOf(DataType.UBYTE, DataType.UWORD)) {
                         // cast right to unsigned
@@ -143,9 +150,16 @@ class TypecastsAdder(val program: Program, val options: CompilationOptions, val
                         return listOf(IAstModification.ReplaceNode(expr.right, cast, expr))
                     }
                     if(rightDt istype DataType.WORD && leftDt.oneOf(DataType.UBYTE, DataType.UWORD)) {
-                        // cast right to unsigned
-                        val cast = TypecastExpression(expr.right, leftDt.getOr(DataType.UNDEFINED), true, expr.right.position)
-                        return listOf(IAstModification.ReplaceNode(expr.right, cast, expr))
+                        // cast right to unsigned word. Cast left to unsigned word if it is ubyte
+                        val mods = mutableListOf<IAstModification>()
+                        val cast = TypecastExpression(expr.right, DataType.UWORD, true, expr.right.position)
+                        mods += IAstModification.ReplaceNode(expr.right, cast, expr)
+                        if(leftDt istype DataType.UBYTE) {
+                            mods += IAstModification.ReplaceNode(expr.left,
+                                TypecastExpression(expr.left, DataType.UWORD, true, expr.left.position),
+                                expr)
+                        }
+                        return mods
                     }
                 }