diff --git a/operator-filter.go b/operator-filter.go
index 459041f..aa679d6 100644
--- a/operator-filter.go
+++ b/operator-filter.go
@@ -52,6 +52,8 @@ func evalFilter(ctx ExprContext, opTerm *term) (v any, err error) {
 				err = fmt.Errorf("filter expression must return a boolean or a castable to boolean, got %v [%T]", rightValue, rightValue)
 			}
 		}
+		ctx.DeleteVar("_count")
+		ctx.DeleteVar("_index")
 		ctx.DeleteVar("_")
 		if err != nil {
 			break
diff --git a/operator-map.go b/operator-map.go
index 7e430c2..ced7e88 100644
--- a/operator-map.go
+++ b/operator-map.go
@@ -46,6 +46,8 @@ func evalMap(ctx ExprContext, opTerm *term) (v any, err error) {
 		if rightValue, err = opTerm.children[1].compute(ctx); err == nil {
 			values.appendItem(rightValue)
 		}
+		ctx.DeleteVar("_count")
+		ctx.DeleteVar("_index")
 		ctx.DeleteVar("_")
 		if err != nil {
 			break