diff --git a/planner/core/expression_rewriter.go b/planner/core/expression_rewriter.go
index 6725335afb196..2691e8cbf9db1 100644
--- a/planner/core/expression_rewriter.go
+++ b/planner/core/expression_rewriter.go
@@ -410,6 +410,7 @@ func (er *expressionRewriter) Enter(inNode ast.Node) (ast.Node, bool) {
 		er.ctxStackAppend(er.schema.Columns[index], er.names[index])
 		return inNode, true
 	case *ast.FuncCallExpr:
+		er.asScalar = true
 		if _, ok := expression.DisableFoldFunctions[v.FnName.L]; ok {
 			er.disableFoldCounter++
 		}