diff --git a/codeCore/src/prog8/code/ast/AstBase.kt b/codeCore/src/prog8/code/ast/AstBase.kt
index df78f7667..9cc9a2bac 100644
--- a/codeCore/src/prog8/code/ast/AstBase.kt
+++ b/codeCore/src/prog8/code/ast/AstBase.kt
@@ -103,6 +103,14 @@ class PtProgram(
 
         children.forEach { transformBinExprToRPN(it, this) }
         binaryExpressionsAreRPN = true
+
+        // extra check to see that all PtBinaryExpressions have been transformed
+        fun binExprCheck(node: PtNode) {
+            if(node is PtBinaryExpression)
+                throw IllegalArgumentException("still got binexpr $node ${node.position}")
+            node.children.forEach { binExprCheck(it) }
+        }
+        binExprCheck(this)
     }
 }