diff --git a/operator-dot.go b/operator-dot.go
index f75837e..f094513 100644
--- a/operator-dot.go
+++ b/operator-dot.go
@@ -47,10 +47,11 @@ func evalDot(ctx ExprContext, self *term) (v any, err error) {
 	indexTerm := self.children[1]
 
 	switch unboxedValue := leftValue.(type) {
-	case []any:
+	case *ListType:
 		var index int
-		if index, err = verifyIndex(ctx, indexTerm, len(unboxedValue)); err == nil {
-			v = unboxedValue[index]
+		array := ([]any)(*unboxedValue)
+		if index, err = verifyIndex(ctx, indexTerm, len(array)); err == nil {
+			v = array[index]
 		}
 	case string:
 		var index int