diff --git a/promql/parser/ast.go b/promql/parser/ast.go
index d9117b988e..da7084300f 100644
--- a/promql/parser/ast.go
+++ b/promql/parser/ast.go
@@ -357,7 +357,7 @@ func Walk(ctx context.Context, v Visitor, s *EvalStmt, node Node, path []Node, n
 		wg.Add(1)
 		go func(i int, e Node) {
 			defer wg.Done()
-			if childNode, childErr := Walk(ctx, v, s, e, append([]Node{}, path...), nr); err != nil {
+			if childNode, childErr := Walk(ctx, v, s, e, append([]Node{}, path...), nr); childErr != nil {
 				errs[i] = childErr
 			} else {
 				newChildren[i] = childNode