diff --git a/codeOptimizers/src/prog8/optimizer/StatementOptimizer.kt b/codeOptimizers/src/prog8/optimizer/StatementOptimizer.kt
index c1db770d5..71bb3c0fa 100644
--- a/codeOptimizers/src/prog8/optimizer/StatementOptimizer.kt
+++ b/codeOptimizers/src/prog8/optimizer/StatementOptimizer.kt
@@ -61,7 +61,7 @@ class StatementOptimizer(private val program: Program,
     }
 
     override fun after(functionCallStatement: FunctionCallStatement, parent: Node): Iterable<IAstModification> {
-        if(functionCallStatement.target.targetStatement(program) is BuiltinFunctionPlaceholder) {
+        if(functionCallStatement.target.nameInSource.size==1) {
             val functionName = functionCallStatement.target.nameInSource[0]
             if (functionName in functions.purefunctionNames) {
                 errors.warn("statement has no effect (function return value is discarded)", functionCallStatement.position)
diff --git a/compilerAst/src/prog8/ast/statements/AstStatements.kt b/compilerAst/src/prog8/ast/statements/AstStatements.kt
index e6660a631..f31969f7c 100644
--- a/compilerAst/src/prog8/ast/statements/AstStatements.kt
+++ b/compilerAst/src/prog8/ast/statements/AstStatements.kt
@@ -49,6 +49,8 @@ sealed class Statement : Node {
 }
 
 
+// this class is only created as temporary result from looking up the target for a builtin function call.
+// this node is never actually part of the Ast.
 class BuiltinFunctionPlaceholder(val name: String, override val position: Position, override var parent: Node) : Statement() {
     override fun linkParents(parent: Node) {}
     override fun accept(visitor: IAstVisitor) = throw FatalAstException("should not iterate over this node")
diff --git a/compilerAst/src/prog8/ast/walk/AstWalker.kt b/compilerAst/src/prog8/ast/walk/AstWalker.kt
index ff31a7825..7c68a791d 100644
--- a/compilerAst/src/prog8/ast/walk/AstWalker.kt
+++ b/compilerAst/src/prog8/ast/walk/AstWalker.kt
@@ -131,7 +131,6 @@ abstract class AstWalker {
     open fun after(branch: ConditionalBranch, parent: Node): Iterable<IAstModification> = noModifications
     open fun after(breakStmt: Break, parent: Node): Iterable<IAstModification> = noModifications
     open fun after(containment: ContainmentCheck, parent: Node): Iterable<IAstModification> = noModifications
-    open fun after(builtinFunctionPlaceholder: BuiltinFunctionPlaceholder, parent: Node): Iterable<IAstModification> = noModifications
     open fun after(decl: VarDecl, parent: Node): Iterable<IAstModification> = noModifications
     open fun after(directive: Directive, parent: Node): Iterable<IAstModification> = noModifications
     open fun after(expr: BinaryExpression, parent: Node): Iterable<IAstModification> = noModifications
diff --git a/docs/source/todo.rst b/docs/source/todo.rst
index 10d31a119..d08b1a993 100644
--- a/docs/source/todo.rst
+++ b/docs/source/todo.rst
@@ -5,6 +5,9 @@ For next release
 ^^^^^^^^^^^^^^^^
 - attempt to rework registerArgsViaStackEvaluation() to use tempvars or push()/pop() instead of evalstack based evaluation
   actually, all function call asmgen code should use the same routine to pass arguments (replaceCallAsmSubStatementWithGosub ?)
+- If all regular function calls (both expression + statement) are then replaced by a GoSub node,
+  the only reason the old FunctionCall[stmt/expression] nodes are still present is because they're for a builtin function call.
+  -> at this time make those a new Node type for the codegenerator
 
 
 Need help with