diff --git a/src/main/java/com/api/jsonata4java/Signature.java b/src/main/java/com/api/jsonata4java/Signature.java
index 3b7529f..52dc7ed 100644
--- a/src/main/java/com/api/jsonata4java/Signature.java
+++ b/src/main/java/com/api/jsonata4java/Signature.java
@@ -383,6 +383,7 @@ ArrayNode validate(String functionName, ExprListContext args, ExpressionsVisitor
                             validatedArgs.add(arg);
                             argIndex++;
                         } else {
+                            arg = expressionVisitor.visit(args.expr(argIndex));
                             validatedArgs.add(arg);
                             argIndex++;
                         }