diff --git a/app/vmselect/promql/eval.go b/app/vmselect/promql/eval.go
index 84bbd894e1..9768ddfae9 100644
--- a/app/vmselect/promql/eval.go
+++ b/app/vmselect/promql/eval.go
@@ -295,7 +295,8 @@ func evalExpr(ec *EvalConfig, e metricsql.Expr) ([]*timeseries, error) {
 		wg.Add(1)
 		go func() {
 			defer wg.Done()
-			tss, err := evalExpr(ec, be.Left)
+			ecCopy := *ec
+			tss, err := evalExpr(&ecCopy, be.Left)
 			mu.Lock()
 			if err != nil {
 				if errGlobal == nil {
@@ -308,7 +309,8 @@ func evalExpr(ec *EvalConfig, e metricsql.Expr) ([]*timeseries, error) {
 		wg.Add(1)
 		go func() {
 			defer wg.Done()
-			tss, err := evalExpr(ec, be.Right)
+			ecCopy := *ec
+			tss, err := evalExpr(&ecCopy, be.Right)
 			mu.Lock()
 			if err != nil {
 				if errGlobal == nil {